Polipo caching web proxy support

plans/polipo/README.md

@@ -0,0 +1,5 @@
+This plan builds and configures the [polipo](https://www.irif.univ-paris-diderot.fr/~jch/software/polipo/) caching web proxy. After you deploy a dockerized polipo, you can use it as a caching proxy for Habitat by exporting it in your shell.
+
+    http_proxy=http://192.168.142.180:8123; export http_proxy
+
+It appears that not every Habitat command utilizes the `http_proxy` environment variable yet, but those that do produce decidedly faster builds.

plans/polipo/config/polipo.config

@@ -0,0 +1,6 @@
+disableIndexing = false
+disableServersList = false
+diskCacheRoot = "{{pkg.svc_path}}/cache/"
+dnsNameServer = "8.8.8.8"
+proxyAddress = "::0"
+proxyPort = {{cfg.port}}

plans/polipo/default.toml

@@ -0,0 +1,2 @@
+# The port number that is listening for requests.
+port=8123

plans/polipo/hooks/init

@@ -0,0 +1,4 @@
+#!/bin/sh
+#
+
+mkdir {{pkg.svc_path}}/cache/

plans/polipo/hooks/run

@@ -0,0 +1,5 @@
+#!/bin/sh
+#
+
+cd {{pkg.svc_path}}
+polipo -c {{pkg.svc_path}}/config/polipo.config

plans/polipo/plan.sh

@@ -0,0 +1,24 @@
+pkg_name=polipo
+pkg_origin=core
+pkg_version=1.1.1
+pkg_maintainer="The Habitat Maintainers <[email protected]>"
+pkg_license=('mit')
+pkg_source=https://github.com/jech/polipo/archive/${pkg_name}-${pkg_version}.tar.gz
+pkg_shasum=de0afeeaa47df776420e59b69e9a78f68e8a7bc4a46b739772e1d91119ed2405
+pkg_deps=(core/glibc)
+pkg_build_deps=(core/gcc core/make)
+pkg_bin_dirs=(bin)
+pkg_include_dirs=(include)
+pkg_lib_dirs=(lib)
+pkg_expose=(8123)
+
+pkg_dirname="${pkg_name}-${pkg_name}-${pkg_version}"
+
+do_build() {
+  make
+}
+
+do_install() {
+  mkdir $pkg_prefix/bin/
+  cp polipo $pkg_prefix/bin/
+}