Decrease docker image from 145MB to 61MB

[siggy]

The Dockerfile was built on linkerd.io/base, which included debug
tools that increased its size.

Build the Docker image directly on debian, only installing iptables.
Also remove the dependency on linkerd.io/go-deps, and instead build
directly off of golang, using Go Modules for dependencies.

Similar to linkerd/linkerd2#3384

Signed-off-by: Andrew Seigner siggy@buoyant.io

[alpeb]

Thanks @siggy that worked great 👍

I built the image locally, consumed it from linkerd2, and it worked fine 👍

$ docker images |grep init
gcr.io/linkerd-io/proxy-init              latest                  2e776083bd91        16 minutes ago      61.4MB
gcr.io/linkerd-io/proxy-init              v1.1.0                  d953961f6d9b        3 weeks ago         145MB

Unit tests:

$ go test ./...
?       github.com/linkerd/linkerd2-proxy-init  [no test files]
ok      github.com/linkerd/linkerd2-proxy-init/cmd      (cached)
ok      github.com/linkerd/linkerd2-proxy-init/integration_test/iptables        0.002s
?       github.com/linkerd/linkerd2-proxy-init/integration_test/iptables/test_service   [no test files]
?       github.com/linkerd/linkerd2-proxy-init/iptables [no test files]

Integration tests:

$ ./run_tests.sh

Deleting any existing objects from previous test runs...
pod "pod-with-no-rules" deleted
service "svc-pod-with-no-rules" deleted
pod "pod-redirects-all-ports" deleted
service "svc-pod-redirects-all-ports" deleted
pod "pod-redirects-whitelisted" deleted
pod "pod-doesnt-redirect-blacklisted" deleted
Error from server (NotFound): jobs.batch "iptables-tester" not found

Building the image used in tests...
Sending build context to Docker daemon  23.04kB
Step 1/3 : FROM golang:1.11.5
 ---> 1454e2b3d01f
Step 2/3 : ADD iptables/ /go
 ---> Using cache
 ---> da8ea10e6b11
Step 3/3 : ENTRYPOINT cd /go && (go test -v -integration-tests; echo "status:$?")
 ---> Using cache
 ---> 706f14fea1a5
Successfully built 706f14fea1a5
Successfully tagged buoyantio/iptables-tester:v1

Creating the test lab...
pod/pod-with-no-rules created
service/svc-pod-with-no-rules created
pod/pod-redirects-all-ports created
service/svc-pod-redirects-all-ports created
pod/pod-redirects-whitelisted created
pod/pod-doesnt-redirect-blacklisted created
POD_WITH_NO_RULES_IP=10.1.3.74
POD_REDIRECTS_ALL_PORTS_IP=10.1.3.75
POD_REDIRECTS_WHITELISTED_IP=10.1.3.76
POD_DOEST_REDIRECT_BLACKLISTED_IP=10.1.3.77

Running tester...
job.batch/iptables-tester created
.............................................................True

Test output:
=== RUN   TestPodWithNoRules
=== PAUSE TestPodWithNoRules
=== RUN   TestPodRedirectsAllPorts
=== PAUSE TestPodRedirectsAllPorts
=== RUN   TestPodWithSomePortsRedirected
=== PAUSE TestPodWithSomePortsRedirected
=== RUN   TestPodWithSomePortsIgnored
=== PAUSE TestPodWithSomePortsIgnored
=== RUN   TestPodMakesOutboundConnection
=== PAUSE TestPodMakesOutboundConnection
=== CONT  TestPodWithNoRules
=== RUN   TestPodWithNoRules/succeeds_connecting_to_pod_directly_through_container's_exposed_port
Expecting successful GET to http://10.1.3.74:8080/
=== CONT  TestPodWithSomePortsIgnored
=== RUN   TestPodWithSomePortsIgnored/succeeds_connecting_to_pod_directly_through_container's_exposed_port
Expecting successful GET to http://10.1.3.77:8080/
=== CONT  TestPodWithSomePortsRedirected
=== RUN   TestPodWithSomePortsRedirected/succeeds_connecting_to_pod_directly_through_container's_exposed_port
Expecting successful GET to http://10.1.3.76:8080/
=== CONT  TestPodRedirectsAllPorts
=== RUN   TestPodRedirectsAllPorts/succeeds_connecting_to_pod_directly_through_container's_exposed_port
Expecting successful GET to http://10.1.3.75:8080/
=== CONT  TestPodMakesOutboundConnection
=== RUN   TestPodMakesOutboundConnection/connecting_to_another_pod_from_non-proxy_container_gets_redirected_to_proxy
Expecting successful GET to http://10.1.3.77:7070/call?url=http%3A%2F%2F10.1.3.74%3A7070
Response from http://10.1.3.75:8080/: proxy
=== RUN   TestPodRedirectsAllPorts/succeeds_connecting_to_pod_directly_through_any_port_that_isn't_the_container's_exposed_port
Response from http://10.1.3.77:8080/: proxy
=== RUN   TestPodWithSomePortsIgnored/succeeds_connecting_to_pod_directly_through_ports_configured_to_redirect
Expecting successful GET to http://10.1.3.77:9090/
Response from http://10.1.3.74:8080/: pod-with-no-rules:8080
=== RUN   TestPodWithNoRules/fails_to_connect_to_pod_directly_through_any_port_that_isn't_the_container's_exposed_port
Expecting failed GET to http://10.1.3.74:8088/
Response from http://10.1.3.76:8080/: proxy
=== RUN   TestPodWithSomePortsRedirected/succeeds_connecting_to_pod_directly_through_ports_configured_to_redirect
Expecting successful GET to http://10.1.3.76:9090/
Response from http://10.1.3.77:7070/call?url=http%3A%2F%2F10.1.3.74%3A7070: me:[pod-doesnt-redirect-blacklisted:7070]downstream:[proxy]
=== RUN   TestPodMakesOutboundConnection/connecting_to_another_pod_from_proxy_container_does_not_get_redirected_to_proxy
Expecting successful GET to http://10.1.3.77:8080/call?url=http%3A%2F%2F10.1.3.74%3A9090
Expecting successful GET to http://10.1.3.75:8088/
Expecting failed GET to http://10.1.3.74:8888/
Expecting failed GET to http://10.1.3.74:8988/
=== RUN   TestPodWithNoRules/succeeds_connecting_to_pod_via_a_service_through_container's_exposed_port
Expecting successful GET to http://svc-pod-with-no-rules:8080/
Response from http://10.1.3.77:9090/: proxy
Expecting successful GET to http://10.1.3.77:9099/
Response from http://10.1.3.77:8080/call?url=http%3A%2F%2F10.1.3.74%3A9090: me:[proxy]downstream:[pod-with-no-rules:9090]
Response from http://10.1.3.77:9099/: proxy
=== RUN   TestPodMakesOutboundConnection/connecting_to_loopback_from_non-proxy_container_does_not_get_redirected_to_proxy
Expecting successful GET to http://10.1.3.77:7070/call?url=http%3A%2F%2F127.0.0.1%3A9090
=== RUN   TestPodWithSomePortsIgnored/doesnt_redirect_when_through_port_that_is_ignored
Expecting successful GET to http://10.1.3.77:7070/
Response from http://10.1.3.76:9090/: proxy
Expecting successful GET to http://10.1.3.76:9099/
Response from http://10.1.3.75:8088/: proxy
Expecting successful GET to http://10.1.3.75:8888/
Response from http://10.1.3.77:7070/call?url=http%3A%2F%2F127.0.0.1%3A9090: me:[pod-doesnt-redirect-blacklisted:7070]downstream:[pod-doesnt-redirect-blacklisted:9090]
--- PASS: TestPodMakesOutboundConnection (0.01s)
    --- PASS: TestPodMakesOutboundConnection/connecting_to_another_pod_from_non-proxy_container_gets_redirected_to_proxy (0.00s)
    --- PASS: TestPodMakesOutboundConnection/connecting_to_another_pod_from_proxy_container_does_not_get_redirected_to_proxy (0.00s)
    --- PASS: TestPodMakesOutboundConnection/connecting_to_loopback_from_non-proxy_container_does_not_get_redirected_to_proxy (0.00s)
Response from http://10.1.3.75:8888/: proxy
Expecting successful GET to http://10.1.3.75:8988/
Response from http://10.1.3.76:9099/: proxy
=== RUN   TestPodWithSomePortsRedirected/fails_to_connect_to_pod_via_through_any_port_that_isn't_configured_to_redirect
Expecting failed GET to http://10.1.3.76:8088/
Expecting failed GET to http://10.1.3.76:8888/
Expecting failed GET to http://10.1.3.76:8988/
Response from http://10.1.3.75:8988/: proxy
=== RUN   TestPodRedirectsAllPorts/succeeds_connecting_to_pod_via_a_service_through_container's_exposed_port
Expecting successful GET to http://svc-pod-redirects-all-ports:8080/
--- PASS: TestPodWithSomePortsRedirected (0.01s)
    --- PASS: TestPodWithSomePortsRedirected/succeeds_connecting_to_pod_directly_through_container's_exposed_port (0.00s)
    --- PASS: TestPodWithSomePortsRedirected/succeeds_connecting_to_pod_directly_through_ports_configured_to_redirect (0.01s)
    --- PASS: TestPodWithSomePortsRedirected/fails_to_connect_to_pod_via_through_any_port_that_isn't_configured_to_redirect (0.00s)
Response from http://10.1.3.77:7070/: pod-doesnt-redirect-blacklisted:7070
--- PASS: TestPodWithSomePortsIgnored (0.01s)
    --- PASS: TestPodWithSomePortsIgnored/succeeds_connecting_to_pod_directly_through_container's_exposed_port (0.00s)
    --- PASS: TestPodWithSomePortsIgnored/succeeds_connecting_to_pod_directly_through_ports_configured_to_redirect (0.00s)
    --- PASS: TestPodWithSomePortsIgnored/doesnt_redirect_when_through_port_that_is_ignored (0.00s)
Response from http://svc-pod-with-no-rules:8080/: pod-with-no-rules:8080
=== RUN   TestPodWithNoRules/fails_to_connect_to_pod_via_a_service_through_any_port_that_isn't_the_container's_exposed_port
Expecting failed GET to http://svc-pod-with-no-rules:8088/
Response from http://svc-pod-redirects-all-ports:8080/: proxy
=== RUN   TestPodRedirectsAllPorts/fails_to_connect_to_pod_via_a_service_through_any_port_that_isn't_the_container's_exposed_port
Expecting failed GET to http://svc-pod-redirects-all-ports:8088/
Expecting failed GET to http://svc-pod-with-no-rules:8888/
Expecting failed GET to http://svc-pod-redirects-all-ports:8888/
Expecting failed GET to http://svc-pod-redirects-all-ports:8988/
Expecting failed GET to http://svc-pod-with-no-rules:8988/
--- PASS: TestPodWithNoRules (61.08s)
    --- PASS: TestPodWithNoRules/succeeds_connecting_to_pod_directly_through_container's_exposed_port (0.00s)
    --- PASS: TestPodWithNoRules/fails_to_connect_to_pod_directly_through_any_port_that_isn't_the_container's_exposed_port (0.00s)
    --- PASS: TestPodWithNoRules/succeeds_connecting_to_pod_via_a_service_through_container's_exposed_port (0.01s)
    --- PASS: TestPodWithNoRules/fails_to_connect_to_pod_via_a_service_through_any_port_that_isn't_the_container's_exposed_port (61.07s)
--- PASS: TestPodRedirectsAllPorts (61.09s)
    --- PASS: TestPodRedirectsAllPorts/succeeds_connecting_to_pod_directly_through_container's_exposed_port (0.00s)
    --- PASS: TestPodRedirectsAllPorts/succeeds_connecting_to_pod_directly_through_any_port_that_isn't_the_container's_exposed_port (0.01s)
    --- PASS: TestPodRedirectsAllPorts/succeeds_connecting_to_pod_via_a_service_through_container's_exposed_port (0.00s)
    --- PASS: TestPodRedirectsAllPorts/fails_to_connect_to_pod_via_a_service_through_any_port_that_isn't_the_container's_exposed_port (61.08s)
PASS
ok      _/go    61.097s
status:0