422 lines
16 KiB
Plaintext
422 lines
16 KiB
Plaintext
---
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layout: docs
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page_title: ACL Policy Specification
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description: Learn about Nomad's ACL policy specification.
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---
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# ACL Policy Specification
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The [Secure Nomad with Access Control] guide includes step-by-step instructions
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for bootstrapping Nomad's Access Control List (ACL) system, authoring policies,
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and granting policies. This document is a detailed reference of the expected
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policy structure and available options.
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ACL policies are written using [HashiCorp Configuration Language
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(HCL)][hcl]. The HCL interpreter can also parse JSON to facilitate
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machine-generated configuration. A detailed syntax specification for HCL can be
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found at [HCL Native Syntax Specification][hcl_syntax_spec].
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All content of an ACL policy is case-sensitive.
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An ACL policy contains one or more **rules**. Each rule block contains a
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combination of `policy` and `capabilities` fields. The specific values permitted
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are described for each rule definition below. An example structure of an ACL
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policy is as follows:
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```hcl
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# this is a namespace rule for the "foo" namespace
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namespace "foo" {
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policy = "write" # this is a policy field
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capabilities = ["alloc-exec"] # this is a capabilities list
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# this block controls access to variables in this namespace
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variables {
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path "project/*" {
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capabilities = ["read", "write"]
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}
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}
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}
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# this is a namespace rule, with a wildcard label
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namespace "*" {
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policy = "read"
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}
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node {
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policy = "read"
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}
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agent {
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policy = "read"
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}
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operator {
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policy = "read"
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}
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quota {
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policy = "read"
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}
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# this is a host_volume rule, with a wildcard label
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host_volume "*" {
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policy = "read"
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}
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plugin {
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policy = "write"
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}
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```
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## Namespace Rules
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Namespace rules are defined with a `namespace` block. An ACL policy can include
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zero, one, or more namespace rules.
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Namespace rules control access to APIs in Nomad that are namespaced:
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[Jobs][api_jobs], [Allocations][api_allocations],
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[Deployments][api_deployments], [Evaluations][api_evaluations],
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[Recommendations][api_recommendations], [Scaling
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Policies][api_scaling_policies], [Services][api_services], and [CSI
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Volumes][api_volumes]. Namespace rules also filter items related to the above
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APIs from the [Event Stream][api_events] and [Search][api_search] APIs.
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Each namespace rule is labeled with the namespace name it applies to. If no
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namespace label is specified, the rule will apply to the "default"
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namespace. You may use wildcard globs (`"*"`) in the namespace label, to apply a
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rule to multiple namespaces.
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Only one namespace rule can apply. When an action is checked against the ACL
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Policy, the namespace rule is selected by first checking for an _exact match_,
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before falling back to a glob-based lookup. When looking up the namespace by
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glob, the matching rule with the greatest number of matched characters will be
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chosen.
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For example the following policy will evaluate to deny for `production-web`,
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because it is 9 characters different from the `"*-web"` rule, but 13 characters
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different from the `"*"` rule.
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```hcl
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namespace "*-web" {
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policy = "deny"
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}
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namespace "*" {
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policy = "write"
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}
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```
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Each namespace rule can include a coarse-grained `policy` field, a fine-grained
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`capabilities` field, a `variables` block, or all three.
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The `policy` field for namespace rules can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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In addition to the coarse-grained `policy`, you can provide a fine-grained list
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of `capabilities`. This includes:
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- `deny` - When multiple policies are associated with a token, deny will take
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precedence and prevent any capabilities.
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- `list-jobs` - Allows listing the jobs and seeing coarse grain status.
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- `parse-job` - Allows parsing a job from HCL to JSON.
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- `read-job` - Allows inspecting a job and seeing fine grain status.
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- `submit-job` - Allows jobs to be submitted, updated, or stopped.
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- `dispatch-job` - Allows jobs to be dispatched
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- `read-logs` - Allows the logs associated with a job to be viewed.
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- `read-fs` - Allows the filesystem of allocations associated to be viewed.
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- `alloc-exec` - Allows an operator to connect and run commands in running
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allocations.
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- `alloc-node-exec` - Allows an operator to connect and run commands in
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allocations running without filesystem isolation, for example, raw_exec jobs.
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- `alloc-lifecycle` - Allows an operator to stop individual allocations
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manually.
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- `csi-register-plugin` - Allows jobs to be submitted that register themselves
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as CSI plugins.
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- `csi-write-volume` - Allows CSI volumes to be registered or deregistered.
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- `csi-read-volume` - Allows inspecting a CSI volume and seeing fine grain
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status.
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- `csi-list-volume` - Allows listing CSI volumes and seeing coarse grain status.
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- `csi-mount-volume` - Allows jobs to be submitted that claim a CSI volume.
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- `list-scaling-policies` - Allows listing scaling policies.
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- `read-scaling-policy` - Allows inspecting a scaling policy.
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- `read-job-scaling` - Allows inspecting the current scaling of a job.
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- `scale-job`: Allows scaling a job up or down.
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- `sentinel-override` - Allows soft mandatory policies to be overridden.
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The coarse-grained policy permissions are shorthand for the following fine-
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grained namespace capabilities:
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<!-- markdownlint-disable -->
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| Policy | Capabilities |
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| ------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `deny` | deny |
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| `read` | list-jobs<br />parse-job<br />read-job<br />csi-list-volume<br />csi-read-volume<br />list-scaling-policies<br />read-scaling-policy<br />read-job-scaling |
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| `write` | list-jobs<br />parse-job<br />read-job<br />submit-job<br />dispatch-job<br />read-logs<br />read-fs<br />alloc-exec<br />alloc-lifecycle<br />csi-write-volume<br />csi-mount-volume<br />list-scaling-policies<br />read-scaling-policy<br />read-job-scaling<br />scale-job |
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| `scale` | list-scaling-policies<br />read-scaling-policy<br />read-job-scaling<br />scale-job |
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<!-- markdownlint-enable -->
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If you provide both a `policy` and `capabilities` list, the capabilities are
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merged. For example, the policy below adds the `submit-job` capability to the `read`
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policy disposition, which provides the `list-job` and `read-job` capabilities:
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```hcl
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# Allow reading jobs and submitting jobs, without allowing access
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# to view log output or inspect the filesystem
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namespace "default" {
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policy = "read"
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capabilities = ["submit-job"]
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}
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```
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A similar policy could also be expressed as:
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```hcl
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# Allow reading jobs and submitting jobs, without allowing access
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# to view log output or inspect the filesystem
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namespace "default" {
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capabilities = ["submit-job","list-jobs","read-job"]
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}
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```
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### Variables
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The `variables` block in the `namespace` rule controls access to
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[Variables][]. The variables block is optional, but you can specify only one
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variables block per namespace rule.
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A `variables` block includes one or more `path` blocks. Each `path` block is
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labeled with the path it applies to. You may use wildcard globs (`"*"`) in the
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path label, to apply the block to multiple paths in the namespace.
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Each path has a list of `capabilities`. The available capabilities for Variables
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are as follows:
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| Capability | Notes |
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|------------|-----------------------------------------------------------------------------------------------------------------------|
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| write | Create or update Variables at this path. Includes the "list" capability but not the "read" or "destroy" capabilities. |
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| read | Read the decrypted contents of Variables at this path. Also includes the "list" capability |
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| list | List the metadata but not contents of Variables at this path. |
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| destroy | Delete Variables at this path. |
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| deny | No permissions at this path. Deny takes precedence over other capabilities. |
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For example, the policy below allows full access to variables at all paths in
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the "dev" namespace that are prefixed with "project/", but only read access to
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paths prefixed with "system/". Note that the glob can match an empty string but
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all other characters are strictly matched. This policy grants read access to
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paths prefixed with "system/" but not a path named "system" (without a trailing
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slash). This policy does not grant any other coarse-grained policy or
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fine-grained capabilities.
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```hcl
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namespace "dev" {
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variables {
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# full access to secrets in all "project" paths
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path "project/*" {
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capabilities = ["write", "read", "destroy", "list"]
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}
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# read/list access within a "system/" path belonging to administrators
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path "system/*" {
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capabilities = ["read"]
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}
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}
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}
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```
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## Node rules
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The `node` rule controls access to the [Node API][api_node] such as listing
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nodes or triggering a node drain. The node rule is optional, but you can specify
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only one node rule per ACL Policy.
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```hcl
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node {
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policy = "read"
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}
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```
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The `policy` field for the node rule can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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## Agent rules
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The `agent` rule controls access to the [Agent API][api_agent] such as join and
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leave. The agent rule is optional, but you can specify only one agent rule per
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ACL Policy.
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```hcl
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agent {
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policy = "read"
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}
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```
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The `policy` field for the agent rule can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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## Operator rules
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The `operator` rule controls access to the [Operator API][api_operator] such
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raft or scheduler configuration. The operator rule is optional, but you can
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specify only one operator rule per ACL Policy.
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```hcl
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operator {
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policy = "read"
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}
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```
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The `policy` field for the operator rule can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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In the example above, the token could be used to query the operator endpoints
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for diagnostic purposes but not make any changes.
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## Quota rules
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The `quota` rule controls access to the [Quota API][api_quota] such as quota
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creation and deletion. The quota rule is optional, but you can specify only one
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quota rule per ACL Policy.
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```hcl
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quota {
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policy = "read"
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}
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```
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The `policy` field for the quota rule can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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## Host Volume rules
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The `host_volume` rule controls access to mounting and accessing [host
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volumes][host_volumes]. An ACL Policy can include zero, one, or more host volume
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rules.
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```hcl
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host_volume "*" {
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policy = "write"
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}
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host_volume "prod-*" {
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policy = "deny"
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}
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host_volume "prod-ca-certificates" {
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policy = "read"
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}
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```
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Host volume rules are labeled with the volume names that they apply to. As with
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namespaces, you may use wildcards to reuse the same configuration across a set
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of volumes.
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The `policy` field for host volume rules can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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In addition to the coarse grained policy, host volume rules can include a list
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of fine-grained `capabilities`. These include:
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- `deny` - Do not allow a user to mount a volume in any way.
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- `mount-readonly` - Only allow the user to mount the volume as `readonly`
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- `mount-readwrite` - Allow the user to mount the volume as `readonly` or
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`readwrite` if the `host_volume` configuration allows it.
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The coarse-grained policy permissions are shorthand for the fine grained
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capabilities:
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<!-- markdownlint-disable -->
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| Policy | Capabilities |
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|---------|-------------------------------------|
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| `deny` | deny |
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| `read` | mount-readonly |
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| `write` | mount-readonly<br />mount-readwrite |
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<!-- markdownlint-enable -->
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When both the policy short hand and a capabilities list are provided, the
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capabilities are merged.
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~> **Note:** Host Volume policies are applied when attempting to _use_ a volume.
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Regardless of this configuration, users with access to the Node API will be able
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to list available volumes using the `nomad node status` command or API call. .
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## Plugin rules
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The `plugin` rule controls access to [CSI plugins][api_plugins], such as listing
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plugins or getting plugin status. The plugin rule is optional, but you can
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specify only one plugin rule per ACL policy.
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```hcl
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plugin {
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policy = "read"
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}
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```
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The `policy` field for the plugin rule can have one of the following values:
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- `read`: allow the resource to be read but not modified
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- `list`: allow the resource to be listed, but not inspected in detail
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- `write`: allow the resource to be read and modified
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- `deny`: do not allow the resource to be read or modified. Deny takes
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precedence when multiple policies are associated with a token.
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## Configuring ACLs for the web UI
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The Nomad web UI uses the API endpoints `/v1/agent` and `/v1/node` for nearly
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every page. ACL policies for users who will use the Nomad UI should include the
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following rules.
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```hcl
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node {
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policy = "read"
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}
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agent {
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policy = "read"
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}
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```
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[Secure Nomad with Access Control]: /nomad/tutorials/access-control
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[hcl]: https://github.com/hashicorp/hcl
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[hcl_syntax_spec]: https://github.com/hashicorp/hcl/blob/main/hclsyntax/spec.md
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[api_jobs]: /nomad/api-docs/jobs
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[api_allocations]: /nomad/api-docs/allocations
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[api_deployments]: /nomad/api-docs/deployments
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[api_evaluations]: /nomad/api-docs/evaluations
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[api_recommendations]: /nomad/api-docs/recommendations
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[api_scaling_policies]: /nomad/api-docs/scaling-policies
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[api_services]: /nomad/api-docs/services
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[api_volumes]: /nomad/api-docs/volumes
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[api_events]: /nomad/api-docs/events
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[api_search]: /nomad/api-docs/search
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[api_agent]: /nomad/api-docs/agent/
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[api_node]: /nomad/api-docs/nodes/
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[api_operator]: /nomad/api-docs/operator/
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[api_quota]: /nomad/api-docs/quotas/
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[host_volumes]: /nomad/docs/configuration/client#host_volume-block
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[api_plugins]: /nomad/api-docs/plugins/
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[Variables]: /nomad/docs/concepts/variables
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