website: switch to prettier demo
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Michael Schurter
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@ -70,107 +70,187 @@ Alternatively if you know the network interface Nomad should use:
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$ sudo nomad agent -dev -network-interface eth0
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```
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## Run Redis Container
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## Run the Connect-enabled Services
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Run the following job specification using `nomad run`. This job uses the
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`network` stanza in its task group with `bridge` networking mode. This enables
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all tasks in the same group to share the same network, and other allocations,
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even on the same node, cannot. The `connect` stanza enables Consul Connect
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functionality for this container. Nomad will launch a proxy for this container
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that registers itself in Consul.
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Once Nomad and Consul are running submit the following Connect-enabled services
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to Nomad by copying the HCL into a file named `connect.nomad` and running:
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`nomad run connect.nomad`
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```hcl
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job "redis" {
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job "countdash" {
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datacenters = ["dc1"]
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group "cache" {
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group "api" {
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network {
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mode = "bridge"
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}
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service {
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name = "redis-cache"
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tags = ["global", "cache"]
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# This is the port within the network namespace that the task listens on.
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# The Envoy proxy itself listens on a random port.
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port = "6379"
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name = "count-api"
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port = "9001"
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connect {
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sidecar_service {}
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}
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}
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task "redis" {
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task "web" {
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driver = "docker"
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config {
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image = "redis:3.2"
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}
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resources {
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cpu = 500
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memory = 256
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image = "hashicorpnomad/counter-api:v1"
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}
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}
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}
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}
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```
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## Run the web application
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#### TODO change the example container
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Run the following job specification using `nomad run`. This container is a web application
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that uses Redis. It declares Redis as its upstream service through the `sidecar_service` stanza.
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It also specifies a local bind port. This is the port on which the proxy providing secure communication
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to Redis listens on.
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```hcl
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job "api" {
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datacenters = ["dc1"]
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group "api" {
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group "dashboard" {
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network {
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mode ="bridge"
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port "http" {
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to = 8080
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static = 8080
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static = 9002
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to = 9002
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}
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}
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service {
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name = "api"
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port = "http"
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name = "count-dashboard"
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port = "9002"
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connect {
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sidecar_service {
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proxy {
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upstreams {
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destination_name = "redis-cache"
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local_bind_port = 6379
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destination_name = "count-api"
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local_bind_port = 8080
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}
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}
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}
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}
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}
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task "api" {
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task "dashboard" {
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driver = "docker"
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config {
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image = "schmichael/rediweb:0.2"
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env {
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COUNTING_SERVICE_URL = "http://${NOMAD_UPSTREAM_ADDR_count_api}"
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}
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resources {
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cpu = 200
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memory = 100
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config {
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image = "hashicorpnomad/counter-dashboard:v1"
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}
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}
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}
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}
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```
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After running this job, visit the Nomad UI to see the Envoy proxies managed by Nomad
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both for the web application and its upstream Redis service. The Consul UI also shows
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the registered Connect proxies.
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The job contains two task groups: an API service and a web frontend.
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### API Service
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The API service is defined as a task group with a bridge network:
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```hcl
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group "api" {
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network {
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mode = "bridge"
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}
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...
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}
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```
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Since the API service is only accessible via Consul Connect, it does not define
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any ports in its network. The service stanza enables Connect:
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```hcl
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group "api" {
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...
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service {
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name = "count-api"
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port = "9001"
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connect {
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sidecar_service {}
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}
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}
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...
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}
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```
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The `port` in the service stanza is the port the API service listens on. The
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Envoy proxy will automatically route traffic to that port inside the network
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namespace.
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### Web Frontend
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The web frontend is defined as a task group with a bridge network and a static
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forwarded port:
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```hcl
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group "dashboard" {
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network {
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mode ="bridge"
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port "http" {
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static = 9002
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to = 9002
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}
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}
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...
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}
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```
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The `static = 9002` parameter requests the Nomad scheduler reserve port 9002 on
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a host network interface. The `to = 9002` parameter forwards that host port to
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port 9002 inside the network namespace.
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This allows you to connect to the web frontend in a browser by visiting
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`http://<host_ip>:9002`.
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The web frontend connects to the API service via Consul Connect:
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```hcl
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service {
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name = "count-dashboard"
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port = "9002"
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connect {
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sidecar_service {
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proxy {
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upstreams {
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destination_name = "count-api"
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local_bind_port = 8080
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}
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}
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}
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}
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}
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```
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The `upstreams` stanza defines the remote service to access (`count-api`) and
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what port to expose that service on inside the network namespace (`8080`).
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The web frontend is configured to communicate with the API service with an
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environment variable:
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```hcl
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env {
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COUNTING_SERVICE_URL = "http://${NOMAD_UPSTREAM_ADDR_count_api}"
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}
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```
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The web frontend is configured via the `$COUNTING_SERVICE_URL`, so you must
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interpolate the upstream's address into that environment variable. Note that
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dashes (`-`) are converted to underscores (`_`) in environment variables so
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`count-api` becomes `count_api`.
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## Limitations
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Prior to Nomad 0.10.0's final release, the Consul Connect integration has
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several limitations that have yet to be addressed:
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- Jobs with a `connect` stanza may not update properly. Workaround this by
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stopping and starting Connect-enabled jobs.
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- Only the Docker, exec, and raw exec drivers support network namespaces and
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Connect.
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- Not all Connect configuration options in Consul are available in Nomad.
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- The Envoy proxy is not yet configurable and is hardcoded to use 100 MHz of
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cpu and 300 MB of memory.
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