nixpkgs/pkgs/build-support/fetchdocker/generic-fetcher.nix
Parnell Springmeyer 25865688a7
docker: init fetchdocker nix code for docker2nix
This change adds granular, non-docker daemon docker image fetchers and
a docker image layer compositor to be used in conjunction with the
`docker2nix` utility provided by the `haskellPackages.hocker` package.

This change includes a hackage package version bump and updated sha256
for recent fixes released to `hocker` resulting from formulating this
patch.
2017-12-01 21:00:52 -06:00

97 lines
3.2 KiB
Nix

{ stdenv, lib, haskellPackages, writeText, gawk }:
let
awk = "${gawk}/bin/awk";
dockerCredentialsFile = import ./credentials.nix;
stripScheme =
builtins.replaceStrings [ "https://" "http://" ] [ "" "" ];
in
{ fetcher
, name
, registry ? "https://registry-1.docker.io/v2/"
, repository ? "library"
, imageName
, sha256
, tag ? ""
, layerDigest ? ""
}:
# There must be no slashes in the repository or container names since
# we use these to make the output derivation name for the nix store
# path
assert null == lib.findFirst (c: "/"==c) null (lib.stringToCharacters repository);
assert null == lib.findFirst (c: "/"==c) null (lib.stringToCharacters imageName);
# Only allow hocker-config and hocker-layer as fetchers for now
assert (builtins.elem fetcher ["hocker-config" "hocker-layer"]);
# If layerDigest is non-empty then it must not have a 'sha256:' prefix!
assert
(if layerDigest != ""
then !lib.hasPrefix "sha256:" layerDigest
else true);
let
layerDigestFlag =
lib.optionalString (layerDigest != "") "--layer ${layerDigest}";
in
stdenv.mkDerivation {
inherit name;
builder = writeText "${fetcher}-builder.sh" ''
source "$stdenv/setup"
header "${fetcher} exporting to $out"
declare -A creds
# This is a hack for Hydra since we have no way of adding values
# to the NIX_PATH for Hydra jobsets!!
staticCredentialsFile="/etc/nix-docker-credentials.txt"
if [ ! -f "$dockerCredentialsFile" -a -f "$staticCredentialsFile" ]; then
echo "credentials file not set, falling back on static credentials file at: $staticCredentialsFile"
dockerCredentialsFile=$staticCredentialsFile
fi
if [ -f "$dockerCredentialsFile" ]; then
header "using credentials from $dockerCredentialsFile"
CREDSFILE=$(cat "$dockerCredentialsFile")
creds[token]=$(${awk} -F'=' '/DOCKER_TOKEN/ {print $2}' <<< "$CREDSFILE" | head -n1)
# Prefer DOCKER_TOKEN over the username and password
# authentication method
if [ -z "''${creds[token]}" ]; then
creds[user]=$(${awk} -F'=' '/DOCKER_USER/ {print $2}' <<< "$CREDSFILE" | head -n1)
creds[pass]=$(${awk} -F'=' '/DOCKER_PASS/ {print $2}' <<< "$CREDSFILE" | head -n1)
fi
fi
# These variables will be filled in first by the impureEnvVars, if
# those variables are empty then they will default to the
# credentials that may have been read in from the 'DOCKER_CREDENTIALS'
DOCKER_USER="''${DOCKER_USER:-''${creds[user]}}"
DOCKER_PASS="''${DOCKER_PASS:-''${creds[pass]}}"
DOCKER_TOKEN="''${DOCKER_TOKEN:-''${creds[token]}}"
${fetcher} --out="$out" \
''${registry:+--registry "$registry"} \
''${DOCKER_USER:+--username "$DOCKER_USER"} \
''${DOCKER_PASS:+--password "$DOCKER_PASS"} \
''${DOCKER_TOKEN:+--token "$DOCKER_TOKEN"} \
${layerDigestFlag} \
"${repository}/${imageName}" \
"${tag}"
stopNest
'';
buildInputs = [ haskellPackages.hocker ];
outputHashAlgo = "sha256";
outputHashMode = "flat";
outputHash = sha256;
preferLocalBuild = true;
impureEnvVars = [ "DOCKER_USER" "DOCKER_PASS" "DOCKER_TOKEN" ];
inherit registry dockerCredentialsFile;
}