Merge #95: Add travis ci builds

aabf4a4730f9c53bbc4f85bc79d79b2d0fc8817d travis: remove cachix push (William Casarin)
8e751c5f3cdac65650f92f771fb4efff88e41622 travis: disable unstable electrs, it is broken (William Casarin)
1e3afa54c5c3b07a0fe3a5ed0e8f86b1db95105c travis: add travis yml (William Casarin)
d7d35b875ac3468b78eec3a8a2c8c5fcce4f38c5 nixpkgs-pinned: fetch a tarball instead (William Casarin)

Pull request description:

  This builds everything to make sure everything works on either the latest release or unstable branch. In the future we could do more interesting nixops builds to test modules, but for now we just nix-build everything and make sure it compiles.

  We test the build with two different versions of nixpkgs:

    - nixpkgs-channels/nixos-19.03
    - nixpkgs-channels/nixos-unstable

ACKs for top commit:
  jonasnick:
    ACK aabf4a4730f9c53bbc4f85bc79d79b2d0fc8817d

Tree-SHA512: 7241552e65fe2e5325f23e271eeb1f87bdf59c85e5dbd8263326d14340bbbee17163d5cb9df3f562c86182b0585ab766fefddea627ee45f0cf8258b85ece6404

.travis.yml

@@ -0,0 +1,35 @@
+language: minimal
+
+# broken:
+#   - PKG=electrs STABLE=0
+
+# Retry installing nix due to nondeterministic error
+#   Fatal error: glibc detected an invalid stdio handle
+# see:
+#   https://github.com/nh2/static-haskell-nix/pull/27#issuecomment-502652181
+#   https://github.com/nixos/nix/issues/2733
+install: |
+  (for i in {1..5}; do bash <(curl https://nixos.org/nix/install) && exit 0; done; exit 1)
+  . /home/travis/.nix-profile/etc/profile.d/nix.sh
+  nix-env -iA cachix -f https://cachix.org/api/v1/install
+  cachix use nix-bitcoin
+  [ $STABLE -eq 1 ] && export NIX_PATH="nixpkgs=$(nix eval --raw -f pkgs/nixpkgs-pinned.nix nixpkgs)"
+  [ $STABLE -eq 0 ] && export NIX_PATH="nixpkgs=$(nix eval --raw -f pkgs/nixpkgs-pinned.nix nixpkgs-unstable)"
+  VER="$(nix eval nixpkgs.lib.version)"
+env:
+  matrix:
+  - PKG=nodeinfo STABLE=1
+  - PKG=hwi STABLE=1
+  - PKG=hwi STABLE=0
+  - PKG=lightning-charge STABLE=1
+  - PKG=lightning-charge STABLE=0
+  - PKG=nanopos STABLE=1
+  - PKG=nanopos STABLE=0
+  - PKG=spark-wallet STABLE=1
+  - PKG=spark-wallet STABLE=0
+  - PKG=elementsd STABLE=1
+  - PKG=elementsd STABLE=0
+  - PKG=electrs STABLE=1
+script: |
+  printf '%s (%s)\n' "$NIX_PATH" "$VER"
+  nix-build -A $PKG

pkgs/nixpkgs-pinned.nix

@@ -1,12 +1,7 @@
+let
+  fetch = rev: builtins.fetchTarball "https://github.com/nixos/nixpkgs-channels/archive/${rev}.tar.gz";
+in
 {
-  nixpkgs = builtins.fetchGit {
+  nixpkgs = fetch "e6ad5e75f3bfaab5e7b7f0f128bf13d534879e65";
-    url = "https://github.com/nixos/nixpkgs-channels";
+  nixpkgs-unstable = fetch "765a71f15025ce78024bae3dc4a92bd2be3a8fbf";
-    ref = "nixos-19.03";
-    rev = "e6ad5e75f3bfaab5e7b7f0f128bf13d534879e65";
-  };
-  nixpkgs-unstable = builtins.fetchGit {
-    url = "https://github.com/nixos/nixpkgs-channels";
-    ref = "nixos-unstable";
-    rev = "765a71f15025ce78024bae3dc4a92bd2be3a8fbf";
-  };
 }