https://github.com/concourse/pool-resource

atomically manages the state of the world (e.g. external environments)
https://github.com/concourse/pool-resource

Last synced: about 2 months ago
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atomically manages the state of the world (e.g. external environments)

Host: GitHub
URL: https://github.com/concourse/pool-resource
Owner: concourse
License: apache-2.0
Created: 2015-06-04T21:56:21.000Z (about 11 years ago)
Default Branch: master
Last Pushed: 2025-03-26T18:05:22.000Z (over 1 year ago)
Last Synced: 2025-04-04T12:05:03.593Z (about 1 year ago)
Language: Go
Homepage:
Size: 477 KB
Stars: 57
Watchers: 25
Forks: 36
Open Issues: 17
Metadata Files:
- Readme: README.md
- License: LICENSE
- Codeowners: CODEOWNERS

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# pool-resource

*a pool of locks (modeling semaphores)*

Allows you to lock environments, pipeline flow, or other entities which have to
be interacted with in a serial manner.

This resource is backed by a Git repository, so the configuration is largely the
same as the git-resource.

## Git Repository Structure

```
.
├── aws
│   ├── claimed
│   │   ├── .gitkeep
│   │   └── env-2
│   └── unclaimed
│   ├── .gitkeep
│   └── env-1
├── ping-pong-tables
│   ├── claimed
│   │   └── .gitkeep
│   └── unclaimed
│   ├── .gitkeep
│   └── north-table
└── vsphere
├── claimed
│   ├── .gitkeep
│   └── f3cb3823-a45a-49e8-ab41-e43268494205
└── unclaimed
├── .gitkeep
└── 83ed9977-3a10-4c49-a818-2d7a37693da7
```

This structure represents 3 pools of locks, `aws`, `ping-pong-tables`, and
`vsphere`. The `.gitkeep` files are required to keep the `unclaimed` and
`claimed` directories track-able by Git if there are no files in them.

You will need to mirror this structure in your own lock repository. In other words, initialize an empty repository
and create one directory in the root of the repository for each pool of locks (e.g. `aws`). Inside of each lock pool directory, create one directory
named `claimed` and one directory named `unclaimed`. Inside each `claimed` and `unclaimed` directory, create an empty
filed named `.gitkeep`. Finally, create individual locks by making an empty file inside of the `unclaimed` directory
(assuming you want your lock to be unclaimed by default) with the desired name of the lock (e.g. `env-1`).

## Source Configuration

* `uri`: *Required.* The location of the repository.

* `branch`: *Required.* The branch to track.

* `pool`: *Required.* The logical name of your pool of things to lock.

* `private_key`: *Optional.* Private key to use when pulling/pushing. Ensure it does not require a password.
Example:
```
private_key: |
-----BEGIN RSA PRIVATE KEY-----
MIIEowIBAAKCAQEAtCS10/f7W7lkQaSgD/mVeaSOvSF9ql4hf/zfMwfVGgHWjj+W

DWiJL+OFeg9kawcUL6hQ8JeXPhlImG6RTUffma9+iGQyyBMCGd1l
-----END RSA PRIVATE KEY-----
```

* `private_key_user`: *Optional.* Enables setting `User` in the ssh config.

* `private_key_passphrase`: *Optional.* To unlock `private_key` if it is protected by a passphrase.

* `username`: *Optional.* Username for HTTP(S) auth when pulling/pushing.
This is needed when only HTTP/HTTPS protocol for git is available (which does not support private key auth) and auth is required.

* `password`: *Optional.* Password for HTTP(S) auth when pulling/pushing.

* `git_config`: *Optional.* If specified as (list of pairs `name` and `value`)
it will configure git global options, setting each name with each value.

This can be useful to set options like `credential.helper` or similar.

See the [`git-config(1)` manual page](https://www.kernel.org/pub/software/scm/git/docs/git-config.html)
for more information and documentation of existing git options.

* `retry_delay`: *Optional.* If specified, dictates how long to wait until
retrying to acquire a lock or release a lock. The default is 10 seconds.
Valid values: `60s`, `90m`, `1h`.

* `https_tunnel`: *Optional.* Information about an HTTPS proxy that will be used to tunnel SSH-based git commands over.
Has the following sub-properties:
* `proxy_host`: *Required.* The host name or IP of the proxy server
* `proxy_port`: *Required.* The proxy server's listening port
* `proxy_user`: *Optional.* If the proxy requires authentication, use this username
* `proxy_password`: *Optional.* If the proxy requires authentication, use this password

* `forward_agent`: *Optional.* Enables ForwardAgent SSH option when set to true. Useful when using proxy/jump hosts. Defaults to false.

* `skip_ssl_verification`: *Optional.* Skips git ssl verification by exporting `GIT_SSL_NO_VERIFY=true`.

### Example

Fetching a repo with only 100 commits of history:

``` yaml
- get: source-code
params: {depth: 100}
```

## Behavior

### `check`: Check for changes to the pool.

The repository is cloned (or pulled if already present), and any commits made to the specified pool from the given version on are returned. If no version is
given, the ref for `HEAD` is returned.

### `in`: Fetch an acquired lock.

Outputs 2 files:

* `metadata`: Contains the contents of whatever was in your lock file. This is
useful for environment configuration settings.

* `name`: Contains the name of lock that was acquired.

#### Parameters

* `depth`: *Optional.* If a positive integer is given, *shallow* clone the
repository using the `--depth` option.

### `out`: Acquire, release, add, or remove a lock.

Performs one of the following actions to change the state of the pool.

#### Parameters

One of the following is required.

* `acquire`: If true, we will attempt to move a randomly chosen lock from the
pool's unclaimed directory to the claimed directory. Acquiring will retry
until a lock becomes available.

* `claim`: If set, the specified lock from the pool will be acquired, rather
than a random one (as in `acquire`). Like `acquire`, claiming will retry
until the specific lock becomes available.

* `release`: If set, we will release the lock by moving it from claimed to
unclaimed. The value is the path of the lock to release (a directory
containing `name` and `metadata`), which typically is just the step that
provided the lock (either a `get` to pass one along or a `put` to acquire).

Note: the lock must be available in your job before you can release it. In
other words, a `get` step to fetch metadata about the lock is necessary
before a `put` step can release the lock.

* `add`: If set, we will add a new lock to the pool in the unclaimed state. The
value is the path to a directory containing the files `name` and `metadata`
which should contain the name of your new lock and the contents you would like
in the lock, respectively.

* `add_claimed`: Exactly the same as the `add` param, but adds a lock to the
pool in the *claimed* state.

* `remove`: If set, we will remove the given lock from the pool. The value is
the same as `release`. This can be used for e.g. tearing down an environment,
or moving a lock between pools by using `add` with a different pool in a
second step.

* `update`: If set, we will update an existing lock in the pool.

* If the existing lock is in the unclaimed state we will update it with the
contents of the `metadata` file.
* If no such lock is present in either the claimed or unclaimed state we add a
new lock to the pool in the unclaimed state.
* If the lock is in the claimed state we will wait for it to be unclaimed and
proceed to update it as above.

The value is the path to a directory containing the files `name` and
`metadata` which should contain the name of your new lock and the contents you
would like in the lock, respectively.

* `check`: If set, we will check for an existing claimed lock in the pool and
wait until it becomes unclaimed.

* If there is an existing lock in claimed state: wait until lock is unclaimed
* If there is an existing lock in unclaimed state: no-op
* If no lock exists: fail

The purpose is to simply block until a given lock in a pool is moved from a
claimed state to an unclaimed state. This functionality allows us to build
dependencies between disparate pipelines without the need to `acquire` locks.

Note: the lock must be present to perform a check. In other words, a `get`
step to fetch metadata about the lock is necessary before a `put` step can
check the existence of the lock.

* `check_unclaimed`: If set, we will check for an existing unclaimed lock in the pool and
wait until it becomes claimed.

* If there is an existing lock in unclaimed state: wait until lock is unclaimed
* If there is an existing lock in claimed state: no-op
* If no lock exists: fail

The purpose is to simply block until a given lock in a pool is moved from an
unclaimed state to a claimed state. This functionality allows us to build
dependencies between disparate pipelines without the need to `acquire` locks.

Note: the lock must be present to perform a check. In other words, a `get`
step to fetch metadata about the lock is necessary before a `put` step can
check the existence of the lock.

## Example Concourse Configuration

The following example pipeline models acquiring, passing through, and releasing
a lock based on the example git repository structure:

```
resources:
- name: aws-environments
type: pool
source:
uri: git@github.com:concourse/locks.git
branch: master
pool: aws
private_key: |
-----BEGIN RSA PRIVATE KEY-----
MIIEowIBAAKCAQEAtCS10/f7W7lkQaSgD/mVeaSOvSF9ql4hf/zfMwfVGgHWjj+W

DWiJL+OFeg9kawcUL6hQ8JeXPhlImG6RTUffma9+iGQyyBMCGd1l
-----END RSA PRIVATE KEY-----

jobs:
- name: deploy-aws
plan:
- put: aws-environments
params: {acquire: true}
- task: deploy-aws
file: my-scripts/deploy-aws.yml

- name: test-aws
plan:
- get: aws-environments
passed: [deploy-aws]
- task: test-aws
file: my-scripts/test-aws.yml
- put: aws-environments
params: {release: aws-environments}
```

### Managing multiple locks

The parameter for `release` is the name of the step whose lock to release.
Normally this is just the same as the name of the resource, but if you have
custom names for `put` (for example if you need to acquire multiple instances
of the same pool), you would put that name instead. For example:

```
- name: test-multi-aws
plan:
- put: environment-1
resource: aws-environments
params: {acquire: true}
- put: environment-2
resource: aws-environments
params: {acquire: true}
- task: test-multi-aws
file: my-scripts/test-multi-aws.yml
- put: aws-environments
params: {release: environment-1}
- put: aws-environments
params: {release: environment-2}
```

### Claiming a specific lock from a pool, and releasing

The parameter for `claim` takes the name of a lock, and releasing the
lock requires the name of the step which acquired the lock. For
example:

```
- name: test-specific-aws
plan:
- put: specific-aws-env
resource: aws-environments
params: {claim: env-1}
- put: aws-environments
params: {release: specific-aws-env}
```

### Configuring resource to proxy SSH commands through an HTTP proxy

## Development

### Prerequisites

* golang is *required* - version 1.9.x is tested; earlier versions may also
work.
* docker is *required* - version 17.06.x is tested; earlier versions may also
work.
* godep is used for dependency management of the golang packages.

### Running the tests

The tests have been embedded with the `Dockerfile`; ensuring that the testing
environment is consistent across any `docker` enabled platform. When the docker
image builds, the test are run inside the docker container, on failure they
will stop the build.

Run the tests with the following command:

```sh
docker build -t pool-resource --target tests .
```

#### Note about the integration tests

If you want to run the integration tests, a bit more work is required. You will require
an actual git repo to which you can push and pull, configured for SSH access. To do this,
add two files to `integration-tests/ssh` (note that names **are** important):
* `test_key`: This is the private key used to authenticate against your repo.
* `test_repo`: This file contains one line of the form `test_repo_url[#test_branch]`.
If the branch is not specified, it defaults to `main`. For example,
`git@github.com:concourse-git-tester/git-resource-integration-tests.git` or
`git@github.com:concourse-git-tester/git-resource-integration-tests.git#testing`

To set up or reset the contents of the repo, use the `integration-tests/ssh/init-repo.sh` script.
The script clones the configured repository, (re-)creates the relevant directories,
commits and pushes the changes. If you'd rather execute the commands yourself, view the script
contents to understand the directory structure expected by the integration tests.

Then run the tests:

```sh
docker build -t pool-resource --target integrationtests .
```

### Contributing

Please make all pull requests to the `master` branch and ensure tests pass
locally.

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