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 # Cloud Identity Broker
 
-// TODO: https://docs.gitlab.com/ee/api/jobs.html#get-job-tokens-job
-// TODO: Admin UI
+This is a cloud identity broker. Identity brokers exist to bridge
+authentication from one system into authentication to another system. In the
+case of this broker it bridges GitHub and GitLab authentication into temporary
+credentials for cloud providers. The broker has an interactive API that can be
+used in a web browser as well as a JSON/REST API that can be consumed
+programmatically.
 
+The reason this broker exists is to provide one secured location for long-lived
+cloud provider credentials that can be easily consumed from development
+environments and build systems while limiting the scope of access and time frame
+of access those systems have to cloud resources. This helps to increase the
+security of those accounts and reduce the risk of abuse. All access through the
+broker is chained to an authenticated and authorized user account and all
+access through those user accounts are logged for auditing. All credentials
+returned by the broker have a strict time limit after which they are useless.
 
+This broker started life as a piece of internal infrastructure specific to AWS
+that has been re-written and open sourced with the goal to support multiple
+clouds.
+
+For documentation the REST API look at the `README_BROKER.md` file.
+
+## Contributing
+
+Contributions are welcomed. Please send contributions to mike-at-crute-dot-us
+either through email in `git format-patch` format or send a link to a git repo
+and branch name that the author can pull and merge.
+
+If you're reading this on one of the author's git forge accounts (GitHub,
+GitLab, sr.ht, etc...) feel free to open a pull/merge request with your
+changes.
+
+The author reserves the right to request changes to contributions before
+merging them or to not merge them at all but will endeavour to be reasonable in
+those requests.
+
+## Building
+
+This requires Go 1.17 or newer to build. Provided that a simple `make` should
+create a `cloud-identity-broker` binary that's ready to use.
+
+The built binary embeds all of the templates in production mode and will
+require nothing more than the binary itself to run, if running in `--debug`
+mode then the `templates` folder must be available.
+
+## Running
+
+It's complicated, so probably don't?
+
+The application requires some bits of infrastructure to be in place for it to
+run but then can be exposed directly to the internet or put behind a reverse
+proxy. You will need:
+
+- [Mongodb](https://www.mongodb.com/)
+- [Vault](https://www.hashicorp.com/products/vault)
+- [GitHub Oauth Application](https://docs.github.com/en/developers/apps/building-oauth-apps/creating-an-oauth-app)
+- [SSL certificates](https://letsencrypt.org/).
+
+Once the requisite infrastructure (see below) is configured, run the binary
+like so:
+
+```
+VAULT_ROLE_ID="..." \
+VAULT_SECRET_ID="..." \
+VAULT_ADDR="https://your-vault-addr:8200" \
+    ./cloud-identity-broker \
+                --mongodb-uri="mongodb://your-mongodb-host:27017/your-db-name?authSource=admin" \
+                --mongodb-vault-path="database/static-creds/your-cred-name" \
+                --github-oauth-vault-path="service/service-name/github-oauth" \
+                web
+```
+
+### SSL Certificates
+
+SSL certificates of a cipher type compatible with Go's SSL library are required
+to run the binary, even in development mode. Obtain those certificates however
+you would normal do so.
+
+Both a key and certificate are required to be stored in the directory
+identified by `--tls-cache-dir` (which defaults to `./ssl/`). Both files should
+be of PEM format with the certificate named `cert.pem` and the key named
+`key.pem`.
+
+### Vault Setup
+
+Configure Vault per the manufacturers instructions. Create an AppRole for the
+identity broker and provide the credentials to the binary using the standard
+Vault environment variables.
+
+The binary will need access to a set of GitHub Oauth client credentials for a
+GitHub Oauth application that is used to authenticate users to the broker.
+Setup an application on GitHub and store the client ID and client secret in a
+JSON document in Vault the vault KV backend with the following format:
+
+```
+{
+    "client-id": "your client id",
+    "client-secret": "your client secret"
+}
+```
+
+Provide the path to this material with the `--github-oauth-vault-path` command
+line argument. You should omit the `kv/data/` prefix to the path.
+
+For each AWS cloud account to which the broker provides access a JSON document
+must be stored in the Vault KV backend. The format of this document is as
+follows. The path to this document is provided (with the `kv/data/` prefix
+omitted)  in the `VaultMaterial` field of the `Account` record for the account
+in Mongodb.
+
+```
+{
+    "AccessKeyId": "...",
+    "SecretAccessKey": "...",
+    "Roles": {
+        "account-short-name": {
+            "ARN": "arn:aws:iam::...:role/...",
+            "ExternalId": "..."
+        }
+    }
+}
+```
+
+The fields are:
+
+- `AccessKeyId` which is the access key ID of an IAM user that can assume roles
+  in the target account.
+- `SecretAccessKey` is the secret key for the IAM user identified by the access
+  key ID.
+- `Roles` is a mapping of account `ShortName` to an AWS ARN and ExternalId used
+  for assuming roles. The `ARN` is the role to be assumed and the `ExternalId`
+  is the External ID configured in the role trust policy.
+
+Note that this application does **not** use the AWS Vault backend to assume
+roles due to limitations AWS places on roles assumed using assumed role
+credentials and not user credentials.
+
+Finally the broker will need access to a Mongodb credential. Currently this
+requires a static credential but in the future a dynamic credential will be
+acceptable. Create this credential and pass it in the `--mongodb-vault-path`
+argument. It should have the form `database/static-creds/your-cred-name`.
+
+### Mongodb Setup
+
+The application needs a Mongodb database with at least a `users` collection
+created. The rest are optional.
+
+To create the `users` collection insert a record to the collection that
+contains your GitHub username as the `_id` field and has `IsAdmin` set to true.
+For example:
+
+```
+db.users.insert({ "_id": "mcrute", "IsAdmin": true })
+```
+
+This is adequate to allow login via GitHub for the named user. All other fields
+will be populated automatically by the app.
+
+To create allowed AWS accounts for use in the broker add them to the `accounts`
+collection. Those records have the following form:
+
+```
+{
+    "_id": "acocunt-short-name",
+    "AccountNumber": 12345,
+    "AccountType": "aws",
+    "ConsoleSessionDuration": 21600000000000,
+    "DefaultRegion": "us-west-2",
+    "Name": "Some Description",
+    "Users": [
+        "username1",
+        "username2"
+    ],
+    "VaultMaterial": "some/path/as/above"
+}
+```
+
+- `_id` is the short name of the account. This must also map into a Vault
+  material per above.
+- `AccountNumber` is the AWS account number for the account being brokered.
+- `AccountType` is the string `aws` for now
+- `ConsoleSessionDuration` is the number of nanoseconds a console session can
+  exist before timing out. (Nanoseconds are silly, yes; it's a serialized
+  time.Time)
+- `DefaultRegion` is the region considered default, this is just used as an
+  indicator in the JSON API.
+- `Name` a longer form, descriptive name of the account.
+- `Users` a case-sensitive list of GitHub user names that have access to this
+  account
+- `VaultMaterial` the path to the Vault material that contains the account
+  credentials document, as above.
+
+## To Do
+
+- Allow GitLab CI jobs to auth using [job tokens](https://docs.gitlab.com/ee/api/jobs.html#get-job-tokens-job)
+- Implement an Admin UI, all admin ops are directly on the DB at the moment
+- Support dynamic mongodb credentials
+- Support for other clouds
+  - GCP
+  - OCI
+  - Azure
+
+## Contributors
+
+- [Mike Crute](https://mike.crute.us)