Goose
39b1d0abc2
Replaces `export GH_TOKEN` with a file-based approach using `$AGENT_HOME/.gh-token`. Each agent writes its token to its own file path, avoiding env-var collisions when multiple agents generate tokens concurrently. Co-Authored-By: Paperclip <noreply@paperclip.ing>
89 lines
3.1 KiB
Markdown
89 lines
3.1 KiB
Markdown
---
|
|
name: github-app-token
|
|
description: Generate a GitHub installation access token from a GitHub App PEM key, App ID, and Installation ID, write it to a per-agent file, then authenticate the gh CLI with it.
|
|
---
|
|
|
|
# GitHub App Token Skill
|
|
|
|
Generate a short-lived GitHub installation access token from a GitHub App's credentials and use it to authenticate the `gh` CLI.
|
|
|
|
## Prerequisites
|
|
|
|
The following environment variables MUST be set before invoking this skill:
|
|
|
|
| Variable | Description |
|
|
|---|---|
|
|
| `GITHUB_APP_ID` | The numeric App ID from the GitHub App settings page |
|
|
| `GITHUB_APP_INSTALLATION_ID` | The numeric Installation ID for the target org/user |
|
|
| `GITHUB_APP_PEM_FILE` | Absolute path to the GitHub App's PEM private key file |
|
|
|
|
If any variable is missing, stop and tell the user which ones are required.
|
|
|
|
Requires `openssl`, `curl`, and `jq`.
|
|
|
|
## Generate a Token
|
|
|
|
Build a JWT signed with the App's private key, then exchange it for an installation access token and write it to a file:
|
|
|
|
```bash
|
|
# Base64url helper
|
|
b64enc() { openssl enc -base64 -A | tr '+/' '-_' | tr -d '='; }
|
|
|
|
# Build JWT (valid 10 minutes)
|
|
NOW=$(date +%s)
|
|
HEADER=$(printf '{"alg":"RS256","typ":"JWT"}' | jq -r -c .)
|
|
PAYLOAD=$(printf '{"iat":%s,"exp":%s,"iss":"%s"}' "$NOW" "$((NOW + 600))" "$GITHUB_APP_ID" | jq -r -c .)
|
|
SIGNED=$(printf '%s' "$HEADER" | b64enc).$(printf '%s' "$PAYLOAD" | b64enc)
|
|
SIG=$(printf '%s' "$SIGNED" | openssl dgst -binary -sha256 -sign "$GITHUB_APP_PEM_FILE" | b64enc)
|
|
JWT="${SIGNED}.${SIG}"
|
|
|
|
# Token file — unique per agent to avoid env-var collisions
|
|
GH_TOKEN_FILE="${AGENT_HOME:+${AGENT_HOME}/.gh-token}"
|
|
GH_TOKEN_FILE="${GH_TOKEN_FILE:-$(mktemp)}"
|
|
|
|
# Exchange JWT for installation token and write to file
|
|
curl -s -X POST \
|
|
-H "Authorization: Bearer ${JWT}" \
|
|
-H "Accept: application/vnd.github+json" \
|
|
-H "X-GitHub-Api-Version: 2022-11-28" \
|
|
"https://api.github.com/app/installations/${GITHUB_APP_INSTALLATION_ID}/access_tokens" \
|
|
| jq -r '.token' > "$GH_TOKEN_FILE"
|
|
|
|
chmod 600 "$GH_TOKEN_FILE"
|
|
```
|
|
|
|
The token file path defaults to `$AGENT_HOME/.gh-token` (unique per agent) or a temporary file when `AGENT_HOME` is not set. This avoids env-var collisions when multiple agents generate tokens concurrently.
|
|
|
|
## Authenticate the gh CLI
|
|
|
|
Read the token from the file and log in:
|
|
|
|
```bash
|
|
gh auth login --with-token < "$GH_TOKEN_FILE"
|
|
```
|
|
|
|
To use `GH_TOKEN` in a single command without polluting the environment:
|
|
|
|
```bash
|
|
GH_TOKEN=$(cat "$GH_TOKEN_FILE") gh api user
|
|
```
|
|
|
|
## Cleanup
|
|
|
|
The installation access token expires after 1 hour. To revoke it early and remove the token file:
|
|
|
|
```bash
|
|
curl -s -X DELETE \
|
|
-H "Authorization: Bearer $(cat "$GH_TOKEN_FILE")" \
|
|
-H "Accept: application/vnd.github+json" \
|
|
"https://api.github.com/installation/token"
|
|
rm -f "$GH_TOKEN_FILE"
|
|
```
|
|
|
|
## Security Notes
|
|
|
|
- Never log or echo the PEM key or installation token to stdout in production.
|
|
- The installation token is valid for 1 hour from generation.
|
|
- Store the PEM file with restrictive permissions (`chmod 600`) and never check it into git.
|
|
- The token file is written with mode `600` and should be cleaned up after use.
|