With this change, Agent.New() accepts many of the dependencies instead
of creating them in New. Accepting fully constructed dependencies from
a constructor makes the type easier to test, and easier to change.
There are still a number of dependencies created in Start() which can
be addressed in a follow up.
Previsouly it was done in Agent.Start, which is much later then it needs to be.
The new 'dns' package was required, because otherwise there would be an
import cycle. In the future we should move more of the dns server into
the dns package.
- unexport testing shims, and document their purpose
- resolve a TODO by moving validation to NewBuilder and storing the one
field that is used instead of all of Options
- create a slice with the correct size to avoid extra allocations
This is a small step to allowing Agent to accept its dependencies
instead of creating them in New.
There were two fields in autoconfig.Config that were used exclusively
to load config. These were replaced with a single function, allowing us
to move LoadConfig back to the config package.
Also removed the WithX functions for building a Config. Since these were
simple assignment, it appeared we were not getting much value from them.
AutoConfig will generate local tokens for clients and the ability to use local tokens is gated off of token replication being enabled and being configured with a replication token. Therefore we already have a hard requirement on having token replication enabled, this commit just makes sure to surface that to the operator instead of having to discern what the issue is from RPC errors.
Most of the groundwork was laid in previous PRs between adding the cert-monitor package to extracting the logic of signing certificates out of the connect_ca_endpoint.go code and into a method on the server.
This also refactors the auto-config package a bit to split things out into multiple files.
This implements a solution for #7863
It does:
Add a new config cache.entry_fetch_rate to limit the number of calls/s for a given cache entry, default value = rate.Inf
Add cache.entry_fetch_max_burst size of rate limit (default value = 2)
The new configuration now supports the following syntax for instance to allow 1 query every 3s:
command line HCL: -hcl 'cache = { entry_fetch_rate = 0.333}'
in JSON
{
"cache": {
"entry_fetch_rate": 0.333
}
}
On the servers they must have a certificate.
On the clients they just have to set verify_outgoing to true to attempt TLS connections for RPCs.
Eventually we may relax these restrictions but right now all of the settings we push down (acl tokens, acl related settings, certificates, gossip key) are sensitive and shouldn’t be transmitted over an unencrypted connection. Our guides and docs should recoommend verify_server_hostname on the clients as well.
Another reason to do this is weird things happen when making an insecure RPC when TLS is not enabled. Basically it tries TLS anyways. We should probably fix that to make it clearer what is going on.
The envisioned changes would allow extra settings to enable dynamically defined auth methods to be used instead of or in addition to the statically defined one in the configuration.
There are a couple of things in here.
First, just like auto encrypt, any Cluster.AutoConfig RPC will implicitly use the less secure RPC mechanism.
This drastically modifies how the Consul Agent starts up and moves most of the responsibilities (other than signal handling) from the cli command and into the Agent.
All commands which read config (agent, services, and validate) will now
print warnings when one of the config files is skipped because it did
not match an expected format.
Also ensures that config validate prints all warnings.
Previously the logic for reading ConfigFiles and produces Sources was split
between NewBuilder and Build. This commit moves all of the logic into NewBuilder
so that Build() can operate entirely on Sources.
This change is in preparation for logging warnings when files have an
unsupported extension.
It also reduces the scope of BuilderOpts, and gets us very close to removing
Builder.options.
The nil value was never used. We can avoid a bunch of complications by
making the field a string value instead of a pointer.
This change is in preparation for fixing a silent config failure.
Flags is an overloaded term in this context. It generally is used to
refer to command line flags. This struct, however, is a data object
used as input to the construction.
It happens to be partially populated by command line flags, but
otherwise has very little to do with them.
Renaming this struct should make the actual responsibility of this struct
more obvious, and remove the possibility that it is confused with
command line flags.
This change is in preparation for adding additional fields to
BuilderOpts.
This field was populated for one reason, to test that it was empty.
Of all the callers, only a single one used this functionality. The rest
constructed a `Flags{}` struct which did not set Args.
I think this shows that the logic was in the wrong place. Only the agent
command needs to care about validating the args.
This commit removes the field, and moves the logic to the one caller
that cares.
Also fix some comments.
This allows the operator to disable agent caching for the http endpoint.
It is on by default for backwards compatibility and if disabled will
ignore the url parameter `cached`.
Three of the checks are temporarily disabled to limit the size of the
diff, and allow us to enable all the other checks in CI.
In a follow up we can fix the issues reported by the other checks one
at a time, and enable them.
Based on work done in https://github.com/hashicorp/memberlist/pull/196
this allows to restrict the IP ranges that can join a given Serf cluster
and be a member of the cluster.
Restrictions on IPs can be done separatly using 2 new differents flags
and config options to restrict IPs for LAN and WAN Serf.
This will emit warnings about the configs not doing anything but still allow them to be parsed.
This also added the warnings for enterprise fields that we already had in OSS but didn’t change their enforcement behavior. For example, attempting to use a network segment will cause a hard error in OSS.
* Implements a simple, tcp ingress gateway workflow
This adds a new type of gateway for allowing Ingress traffic into Connect from external services.
Co-authored-by: Chris Piraino <cpiraino@hashicorp.com>
I spent some time today on my local Mac to figure out why Consul 1.6.3+
was not accepting limits.http_max_conns_per_client.
This adds an explicit check on number of file descriptors to be sure
it might work (this is no guarantee as if many clients are reaching
the agent, it might consume even more file descriptors)
Anyway, many users are fighting with RLIMIT_NOFILE, having a clear
message would allow them to figure out what to fix.
Example of message (reload or start):
```
2020-03-11T16:38:37.062+0100 [ERROR] agent: Error starting agent: error="system allows a max of 512 file descriptors, but limits.http_max_conns_per_client: 8192 needs at least 8212"
```
When run in with `-dev` in DevMode, it is not possible to replace
the embeded UI with another one because `-dev` implies `-ui`.
This commit allows this an slightly change the error message
about Consul 0.7.0 which is very old and does not apply to
current version anyway.
This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch:
There are several distinct chunks of code that are affected:
* new flags and config options for the server
* retry join WAN is slightly different
* retry join code is shared to discover primary mesh gateways from secondary datacenters
* because retry join logic runs in the *agent* and the results of that
operation for primary mesh gateways are needed in the *server* there are
some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur
at multiple layers of abstraction just to pass the data down to the right
layer.
* new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers
* the function signature for RPC dialing picked up a new required field (the
node name of the destination)
* several new RPCs for manipulating a FederationState object:
`FederationState:{Apply,Get,List,ListMeshGateways}`
* 3 read-only internal APIs for debugging use to invoke those RPCs from curl
* raft and fsm changes to persist these FederationStates
* replication for FederationStates as they are canonically stored in the
Primary and replicated to the Secondaries.
* a special derivative of anti-entropy that runs in secondaries to snapshot
their local mesh gateway `CheckServiceNodes` and sync them into their upstream
FederationState in the primary (this works in conjunction with the
replication to distribute addresses for all mesh gateways in all DCs to all
other DCs)
* a "gateway locator" convenience object to make use of this data to choose
the addresses of gateways to use for any given RPC or gossip operation to a
remote DC. This gets data from the "retry join" logic in the agent and also
directly calls into the FSM.
* RPC (`:8300`) on the server sniffs the first byte of a new connection to
determine if it's actually doing native TLS. If so it checks the ALPN header
for protocol determination (just like how the existing system uses the
type-byte marker).
* 2 new kinds of protocols are exclusively decoded via this native TLS
mechanism: one for ferrying "packet" operations (udp-like) from the gossip
layer and one for "stream" operations (tcp-like). The packet operations
re-use sockets (using length-prefixing) to cut down on TLS re-negotiation
overhead.
* the server instances specially wrap the `memberlist.NetTransport` when running
with gateway federation enabled (in a `wanfed.Transport`). The general gist is
that if it tries to dial a node in the SAME datacenter (deduced by looking
at the suffix of the node name) there is no change. If dialing a DIFFERENT
datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh
gateways to eventually end up in a server's :8300 port.
* a new flag when launching a mesh gateway via `consul connect envoy` to
indicate that the servers are to be exposed. This sets a special service
meta when registering the gateway into the catalog.
* `proxycfg/xds` notice this metadata blob to activate additional watches for
the FederationState objects as well as the location of all of the consul
servers in that datacenter.
* `xds:` if the extra metadata is in place additional clusters are defined in a
DC to bulk sink all traffic to another DC's gateways. For the current
datacenter we listen on a wildcard name (`server.<dc>.consul`) that load
balances all servers as well as one mini-cluster per node
(`<node>.server.<dc>.consul`)
* the `consul tls cert create` command got a new flag (`-node`) to help create
an additional SAN in certs that can be used with this flavor of federation.
Fixes#7231. Before an agent would always emit a warning when there is
an encrypt key in the configuration and an existing keyring stored,
which is happening on restart.
Now it only emits that warning when the encrypt key from the
configuration is not part of the keyring.
Something similar already happens inside of the server
(agent/consul/server.go) but by doing it in the general config parsing
for the agent we can have agent-level code rely on the PrimaryDatacenter
field, too.
Currently when using the built-in CA provider for Connect, root certificates are valid for 10 years, however secondary DCs get intermediates that are valid for only 1 year. There is no mechanism currently short of rotating the root in the primary that will cause the secondary DCs to renew their intermediates.
This PR adds a check that renews the cert if it is half way through its validity period.
In order to be able to test these changes, a new configuration option was added: IntermediateCertTTL which is set extremely low in the tests.
* Add CreateCSRWithSAN
* Use CreateCSRWithSAN in auto_encrypt and cache
* Copy DNSNames and IPAddresses to cert
* Verify auto_encrypt.sign returns cert with SAN
* provide configuration options for auto_encrypt dnssan and ipsan
* rename CreateCSRWithSAN to CreateCSR
* Use consts for well known tagged adress keys
* Add ipv4 and ipv6 tagged addresses for node lan and wan
* Add ipv4 and ipv6 tagged addresses for service lan and wan
* Use IPv4 and IPv6 address in DNS
* relax requirements for auto_encrypt on server
* better error message when auto_encrypt and verify_incoming on
* docs: explain verify_incoming on Consul clients.
* Update AWS SDK to use PCA features.
* Add AWS PCA provider
* Add plumbing for config, config validation tests, add test for inheriting existing CA resources created by user
* Unparallel the tests so we don't exhaust PCA limits
* Merge updates
* More aggressive polling; rate limit pass through on sign; Timeout on Sign and CA create
* Add AWS PCA docs
* Fix Vault doc typo too
* Doc typo
* Apply suggestions from code review
Co-Authored-By: R.B. Boyer <rb@hashicorp.com>
Co-Authored-By: kaitlincarter-hc <43049322+kaitlincarter-hc@users.noreply.github.com>
* Doc fixes; tests for erroring if State is modified via API
* More review cleanup
* Uncomment tests!
* Minor suggested clean ups
A check may be set to become passing/critical only if a specified number of successive
checks return passing/critical in a row. Status will stay identical as before until
the threshold is reached.
This feature is available for HTTP, TCP, gRPC, Docker & Monitor checks.
Fixes: #5396
This PR adds a proxy configuration stanza called expose. These flags register
listeners in Connect sidecar proxies to allow requests to specific HTTP paths from outside of the node. This allows services to protect themselves by only
listening on the loopback interface, while still accepting traffic from non
Connect-enabled services.
Under expose there is a boolean checks flag that would automatically expose all
registered HTTP and gRPC check paths.
This stanza also accepts a paths list to expose individual paths. The primary
use case for this functionality would be to expose paths for third parties like
Prometheus or the kubelet.
Listeners for requests to exposed paths are be configured dynamically at run
time. Any time a proxy, or check can be registered, a listener can also be
created.
In this initial implementation requests to these paths are not
authenticated/encrypted.
Previously `verify_incoming` was required when turning on `auto_encrypt.allow_tls`, but that doesn't work together with HTTPS UI in some scenarios. Adding `verify_incoming_rpc` to the allowed configurations.
* Allow setting the mesh gateway mode for an upstream in config files
* Add envoy integration test for mesh gateways
This necessitated many supporting changes in most of the other test cases.
Add remote mode mesh gateways integration test
This fixes pathological cases where the write throughput and snapshot size are both so large that more than 10k log entries are written in the time it takes to restore the snapshot from disk. In this case followers that restart can never catch up with leader replication again and enter a loop of constantly downloading a full snapshot and restoring it only to find that snapshot is already out of date and the leader has truncated its logs so a new snapshot is sent etc.
In general if you need to adjust this, you are probably abusing Consul for purposes outside its design envelope and should reconsider your usage to reduce data size and/or write volume.
* Add ui-content-path flag
* tests complete, regex validator on string, index.html updated
* cleaning up debugging stuff
* ui: Enable ember environment configuration to be set via the go binary at runtime (#5934)
* ui: Only inject {{.ContentPath}} if we are makeing a prod build...
...otherwise we just use the current rootURL
This gets injected into a <base /> node which solves the assets path
problem but not the ember problem
* ui: Pull out the <base href=""> value and inject it into ember env
See previous commit:
The <base href=""> value is 'sometimes' injected from go at index
serve time. We pass this value down to ember by overwriting the ember
config that is injected via a <meta> tag. This has to be done before
ember bootup.
Sometimes (during testing and development, basically not production)
this is injected with the already existing value, in which case this
essentially changes nothing.
The code here is slightly abstracted away from our specific usage to
make it easier for anyone else to use, and also make sure we can cope
with using this same method to pass variables down from the CLI through
to ember in the future.
* ui: We can't use <base /> move everything to javascript (#5941)
Unfortuantely we can't seem to be able to use <base> and rootURL
together as URL paths will get doubled up (`ui/ui/`).
This moves all the things that we need to interpolate with .ContentPath
to the `startup` javascript so we can conditionally print out
`{{.ContentPath}}` in lots of places (now we can't use base)
* fixed when we serve index.html
* ui: For writing a ContentPath, we also need to cope with testing... (#5945)
...and potentially more environments
Testing has more additional things in a separate index.html in `tests/`
This make the entire thing a little saner and uses just javascriopt
template literals instead of a pseudo handbrake synatx for our
templating of these files.
Intead of just templating the entire file this way, we still only
template `{{content-for 'head'}}` and `{{content-for 'body'}}`
in this way to ensure we support other plugins/addons
* build: Loosen up the regex for retrieving the CONSUL_VERSION (#5946)
* build: Loosen up the regex for retrieving the CONSUL_VERSION
1. Previously the `sed` replacement was searching for the CONSUL_VERSION
comment at the start of a line, it no longer does this to allow for
indentation.
2. Both `grep` and `sed` where looking for the omment at the end of the
line. We've removed this restriction here. We don't need to remove it
right now, but if we ever put the comment followed by something here the
searching would break.
3. Added `xargs` for trimming the resulting version string. We aren't
using this already in the rest of the scripts, but we are pretty sure
this is available on most systems.
* ui: Fix erroneous variable, and also force an ember cache clean on build
1. We referenced a variable incorrectly here, this fixes that.
2. We also made sure that every `make` target clears ember's `tmp` cache
to ensure that its not using any caches that have since been edited
everytime we call a `make` target.
* added docs, fixed encoding
* fixed go fmt
* Update agent/config/config.go
Co-Authored-By: R.B. Boyer <public@richardboyer.net>
* Completed Suggestions
* run gofmt on http.go
* fix testsanitize
* fix fullconfig/hcl by setting correct 'want'
* ran gofmt on agent/config/runtime_test.go
* Update website/source/docs/agent/options.html.md
Co-Authored-By: Hans Hasselberg <me@hans.io>
* Update website/source/docs/agent/options.html.md
Co-Authored-By: kaitlincarter-hc <43049322+kaitlincarter-hc@users.noreply.github.com>
* remove contentpath from redirectFS struct
* Support for maximum size for Output of checks
This PR allows users to limit the size of output produced by checks at the agent
and check level.
When set at the agent level, it will limit the output for all checks monitored
by the agent.
When set at the check level, it can override the agent max for a specific check but
only if it is lower than the agent max.
Default value is 4k, and input must be at least 1.
This allows addresses to be tagged at the service level similar to what we allow for nodes already. The address translation that can be enabled with the `translate_wan_addrs` config was updated to take these new addresses into account as well.
Roles are named and can express the same bundle of permissions that can
currently be assigned to a Token (lists of Policies and Service
Identities). The difference with a Role is that it not itself a bearer
token, but just another entity that can be tied to a Token.
This lets an operator potentially curate a set of smaller reusable
Policies and compose them together into reusable Roles, rather than
always exploding that same list of Policies on any Token that needs
similar permissions.
This also refactors the acl replication code to be semi-generic to avoid
3x copypasta.
This PR adds two features which will be useful for operators when ACLs are in use.
1. Tokens set in configuration files are now reloadable.
2. If `acl.enable_token_persistence` is set to `true` in the configuration, tokens set via the `v1/agent/token` endpoint are now persisted to disk and loaded when the agent starts (or during configuration reload)
Note that token persistence is opt-in so our users who do not want tokens on the local disk will see no change.
Some other secondary changes:
* Refactored a bunch of places where the replication token is retrieved from the token store. This token isn't just for replicating ACLs and now it is named accordingly.
* Allowed better paths in the `v1/agent/token/` API. Instead of paths like: `v1/agent/token/acl_replication_token` the path can now be just `v1/agent/token/replication`. The old paths remain to be valid.
* Added a couple new API functions to set tokens via the new paths. Deprecated the old ones and pointed to the new names. The names are also generally better and don't imply that what you are setting is for ACLs but rather are setting ACL tokens. There is a minor semantic difference there especially for the replication token as again, its no longer used only for ACL token/policy replication. The new functions will detect 404s and fallback to using the older token paths when talking to pre-1.4.3 agents.
* Docs updated to reflect the API additions and to show using the new endpoints.
* Updated the ACL CLI set-agent-tokens command to use the non-deprecated APIs.
Adds two new configuration parameters "dns_config.use_cache" and
"dns_config.cache_max_age" controlling how DNS requests use the agent
cache when querying servers.
* Support rate limiting and concurrency limiting CSR requests on servers; handle CA rotations gracefully with jitter and backoff-on-rate-limit in client
* Add CSR rate limiting docs
* Fix config naming and add tests for new CA configs
This PR is almost a complete rewrite of the ACL system within Consul. It brings the features more in line with other HashiCorp products. Obviously there is quite a bit left to do here but most of it is related docs, testing and finishing the last few commands in the CLI. I will update the PR description and check off the todos as I finish them over the next few days/week.
Description
At a high level this PR is mainly to split ACL tokens from Policies and to split the concepts of Authorization from Identities. A lot of this PR is mostly just to support CRUD operations on ACLTokens and ACLPolicies. These in and of themselves are not particularly interesting. The bigger conceptual changes are in how tokens get resolved, how backwards compatibility is handled and the separation of policy from identity which could lead the way to allowing for alternative identity providers.
On the surface and with a new cluster the ACL system will look very similar to that of Nomads. Both have tokens and policies. Both have local tokens. The ACL management APIs for both are very similar. I even ripped off Nomad's ACL bootstrap resetting procedure. There are a few key differences though.
Nomad requires token and policy replication where Consul only requires policy replication with token replication being opt-in. In Consul local tokens only work with token replication being enabled though.
All policies in Nomad are globally applicable. In Consul all policies are stored and replicated globally but can be scoped to a subset of the datacenters. This allows for more granular access management.
Unlike Nomad, Consul has legacy baggage in the form of the original ACL system. The ramifications of this are:
A server running the new system must still support other clients using the legacy system.
A client running the new system must be able to use the legacy RPCs when the servers in its datacenter are running the legacy system.
The primary ACL DC's servers running in legacy mode needs to be a gate that keeps everything else in the entire multi-DC cluster running in legacy mode.
So not only does this PR implement the new ACL system but has a legacy mode built in for when the cluster isn't ready for new ACLs. Also detecting that new ACLs can be used is automatic and requires no configuration on the part of administrators. This process is detailed more in the "Transitioning from Legacy to New ACL Mode" section below.
* Add -enable-local-script-checks options
These options allow for a finer control over when script checks are enabled by
giving the option to only allow them when they are declared from the local
file system.
* Add documentation for the new option
* Nitpick doc wording
* Added new Config for SidecarService in ServiceDefinitions.
* WIP: all the code needed for SidecarService is written... none of it is tested other than config :). Need API updates too.
* Test coverage for the new sidecarServiceFromNodeService method.
* Test API registratrion with SidecarService
* Recursive Key Translation 🤦
* Add tests for nested sidecar defintion arrays to ensure they are translated correctly
* Use dedicated internal state rather than Service Meta for tracking sidecars for deregistration.
Add tests for deregistration.
* API struct for agent register. No other endpoint should be affected yet.
* Additional test cases to cover updates to API registrations
* Refactor Service Definition ProxyDestination.
This includes:
- Refactoring all internal structs used
- Updated tests for both deprecated and new input for:
- Agent Services endpoint response
- Agent Service endpoint response
- Agent Register endpoint
- Unmanaged deprecated field
- Unmanaged new fields
- Managed deprecated upstreams
- Managed new
- Catalog Register
- Unmanaged deprecated field
- Unmanaged new fields
- Managed deprecated upstreams
- Managed new
- Catalog Services endpoint response
- Catalog Node endpoint response
- Catalog Service endpoint response
- Updated API tests for all of the above too (both deprecated and new forms of register)
TODO:
- config package changes for on-disk service definitions
- proxy config endpoint
- built-in proxy support for new fields
* Agent proxy config endpoint updated with upstreams
* Config file changes for upstreams.
* Add upstream opaque config and update all tests to ensure it works everywhere.
* Built in proxy working with new Upstreams config
* Command fixes and deprecations
* Fix key translation, upstream type defaults and a spate of other subtele bugs found with ned to end test scripts...
TODO: tests still failing on one case that needs a fix. I think it's key translation for upstreams nested in Managed proxy struct.
* Fix translated keys in API registration.
≈
* Fixes from docs
- omit some empty undocumented fields in API
- Bring back ServiceProxyDestination in Catalog responses to not break backwards compat - this was removed assuming it was only used internally.
* Documentation updates for Upstreams in service definition
* Fixes for tests broken by many refactors.
* Enable travis on f-connect branch in this branch too.
* Add consistent Deprecation comments to ProxyDestination uses
* Update version number on deprecation notices, and correct upstream datacenter field with explanation in docs
* Implementation of Weights Data structures
Adding this datastructure will allow us to resolve the
issues #1088 and #4198
This new structure defaults to values:
```
{ Passing: 1, Warning: 0 }
```
Which means, use weight of 0 for a Service in Warning State
while use Weight 1 for a Healthy Service.
Thus it remains compatible with previous Consul versions.
* Implemented weights for DNS SRV Records
* DNS properly support agents with weight support while server does not (backwards compatibility)
* Use Warning value of Weights of 1 by default
When using DNS interface with only_passing = false, all nodes
with non-Critical healthcheck used to have a weight value of 1.
While having weight.Warning = 0 as default value, this is probably
a bad idea as it breaks ascending compatibility.
Thus, we put a default value of 1 to be consistent with existing behaviour.
* Added documentation for new weight field in service description
* Better documentation about weights as suggested by @banks
* Return weight = 1 for unknown Check states as suggested by @banks
* Fixed typo (of -> or) in error message as requested by @mkeeler
* Fixed unstable unit test TestRetryJoin
* Fixed unstable tests
* Fixed wrong Fatalf format in `testrpc/wait.go`
* Added notes regarding DNS SRV lookup limitations regarding number of instances
* Documentation fixes and clarification regarding SRV records with weights as requested by @banks
* Rephrase docs
* Added log-file flag to capture Consul logs in a user specified file
* Refactored code.
* Refactored code. Added flags to rotate logs based on bytes and duration
* Added the flags for log file and log rotation on the webpage
* Fixed TestSantize from failing due to the addition of 3 flags
* Introduced changes : mutex, data-dir log writes, rotation logic
* Added test for logfile and updated the default log destination for docs
* Log name now uses UnixNano
* TestLogFile is now uses t.Parallel()
* Removed unnecessary int64Val function
* Updated docs to reflect default log name for log-file
* No longer writes to data-dir and adds .log if the filename has no extension
It fixes the following warnings:
agent/config/builder.go:1201: Errorf format %q has arg s of wrong type *string
agent/config/builder.go:1240: Errorf format %q has arg s of wrong type *string
There are also a lot of small bug fixes found when testing lots of things end-to-end for the first time and some cleanup now it's integrated with real CA code.
Daniel Nephin