Add Buildkite pipeline for updating hackage.nix and stackage.nix

Author: rvl

.buildkite/updates.yml

@@ -0,0 +1,16 @@
+steps:
+  - label: 'Update hackage.nix'
+    command:
+      - nix-build -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-18.09.tar.gz -A maintainer-scripts.update-hackage -o update-hackage.sh
+      - echo "+++ Updating hackage.nix"
+      - ./update-hackage.sh
+    agents:
+      system: x86_64-linux
+
+  - label: 'Update stackage.nix'
+    command:
+      - nix-build -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-18.09.tar.gz -A maintainer-scripts.update-stackage -o update-stackage.sh
+      - echo "+++ Updating stackage.nix"
+      - ./update-stackage.sh
+    agents:
+      system: x86_64-linux

scripts/update-external.nix

@@ -4,23 +4,42 @@
 
 with stdenv.lib;
 
-writeScript "update-${name}-nix.sh" ''
-  #!${stdenv.shell}
+let
+  repoHTTPS = "https://github.com/input-output-hk/${name}.nix.git";
+  repoSSH = "git@github.com:input-output-hk/${name}.nix.git";
+  sshKey = "/run/keys/buildkite-${name}-ssh-private";
+in
+  writeScript "update-${name}-nix.sh" ''
+    #!${stdenv.shell}
 
-  set -euo pipefail
+    set -euo pipefail
 
-  export PATH="${makeBinPath [ coreutils glibc git nix-tools cabal-install nix-prefetch-git ]}"
+    export PATH="${makeBinPath [ coreutils glibc git nix-tools cabal-install nix-prefetch-git ]}"
 
-  ${script}
+    ${script}
 
-  git add .
-  git commit --allow-empty -m "Automatic update for $(date)"
+    echo "Committing changes..."
+    export GIT_COMMITTER_NAME="IOHK"
+    export GIT_COMMITTER_EMAIL="devops+nix-tools@iohk.io"
+    export GIT_AUTHOR_NAME="$GIT_COMMITTER_NAME"
+    export GIT_AUTHOR_EMAIL="$GIT_COMMITTER_EMAIL"
+    git add .
+    git commit --allow-empty --message "Automatic update for $(date)"
 
-  rev=$(git rev-parse HEAD)
+    rev=$(git rev-parse HEAD)
 
-  git push
+    if [ -e ${sshKey} ]
+    then
+      echo "Authenticating using SSH with ${sshKey}"
+      export GIT_SSH_COMMAND="ssh -i ${sshKey} -F /dev/null"
+    else
+      echo "There is no SSH key at ${sshKey}"
+      echo "Git push may not work."
+    fi
 
-  cd ..
+    git push ${repoSSH}
 
-  nix-prefetch-git https://github.com/input-output-hk/${name}.nix.git --rev "$rev" | tee ${name}-src.json
-''
+    cd ..
+
+    nix-prefetch-git ${repoHTTPS} --rev "$rev" | tee ${name}-src.json
+  ''

scripts/update-hackage.nix

@@ -3,9 +3,6 @@
 import ./update-external.nix args {
   name = "hackage";
   script = ''
-    # Make sure the hackage index is recent.
-    cabal new-update
-
     # Clone or update the Hackage Nix expressions repo.
     if [ -d hackage.nix ]; then
       cd hackage.nix
@@ -15,6 +12,10 @@ import ./update-external.nix args {
       git clone git@github.com:input-output-hk/hackage.nix.git
     fi
 
+    # Make sure the hackage index is recent.
+    echo "Updating local hackage index..."
+    cabal update
+
     echo "Running hackage-to-nix..."
 
     hackage-to-nix hackage.nix