Create agent

.gitignore

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+# OSX leaves these everywhere on SMB shares
+._*
+
+# OSX trash
+.DS_Store
+
+# Eclipse files
+.classpath
+.project
+.settings/**
+
+# Emacs save files
+*~
+\#*\#
+.\#*
+
+# Vim-related files
+[._]*.s[a-w][a-z]
+[._]s[a-w][a-z]
+*.un~
+Session.vim
+.netrwhist
+
+# NGINX Plus license files
+*.crt
+*.key
+
+# Visual Studio Code settings
+.vscode
+
+# Default certificate and key
+default.pem
+
+# Dockerfiles for building
+/Dockerfile
+
+# Binary
+nginx-ns1-gslb
+
+# Development configuration file
+dev_config.yaml

.travis.yml

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+language: go
+sudo: required
+services:
+  - docker
+go:
+  - "1.11"
+script:
+  - echo "nginx-ns1-gslb - commit:${TRAVIS_COMMIT}"
+  - make BUILD_IN_CONTAINER=0 all
+before_install:
+  - echo "PR Slug:${TRAVIS_PULL_REQUEST_SLUG}"
+  - if [[ "${TRAVIS_PULL_REQUEST_SLUG}" == "nginxinc/nginx-ns1-gslb" || "${TRAVIS_PULL_REQUEST}" == "false" ]]; then
+    wget https://${fossalocation}/${fossafile} && tar xzf ${fossafile}
+    && ./fossa init
+    && FOSSA_API_KEY=${fossapush} ./fossa analyze -t nginx-ns1-gslb -b ${TRAVIS_BRANCH} ; fi

Gopkg.toml

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+# Gopkg.toml example
+#
+# Refer to https://golang.github.io/dep/docs/Gopkg.toml.html
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#   name = "github.com/x/y"
+#   version = "2.4.0"
+#
+# [prune]
+#   non-go = false
+#   go-tests = true
+#   unused-packages = true
+
+
+[prune]
+  go-tests = true
+  unused-packages = true
+
+[[constraint]]
+  name = "github.com/nginxinc/nginx-plus-go-sdk"
+  version = "0.4.0"
+
+[[constraint]]
+  branch = "v2"
+  name = "gopkg.in/ns1/ns1-go.v2"
+
+[[constraint]]
+  name = "gopkg.in/yaml.v2"
+  version = "2.2.2"

LICENSE

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+/*
+ * Copyright (C) 2017 Nginx, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */

Makefile

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+all: container
+
+VERSION = 0.1-1
+TAG = $(VERSION)
+PREFIX = nginx/nginx-ns1-gslb
+
+DOCKER_RUN = docker run --rm -v $(shell pwd):/go/src/github.com/nginxinc/nginx-ns1-gslb
+DOCKER_BUILD_RUN = docker run --rm -v $(shell pwd):/go/src/github.com/nginxinc/nginx-ns1-gslb -w /go/src/github.com/nginxinc/nginx-ns1-gslb/cmd/agent/
+BUILD_IN_CONTAINER = 1
+DOCKERFILEPATH = build
+GOLANG_CONTAINER = golang:1.11
+CONFIG_FILE=configs/example_global.yaml
+
+nginx-ns1-gslb:
+ifeq ($(BUILD_IN_CONTAINER),1)
+	$(DOCKER_BUILD_RUN) -e CGO_ENABLED=0 $(GOLANG_CONTAINER) go build -installsuffix cgo -ldflags "-w" -o /go/src/github.com/nginxinc/nginx-ns1-gslb/nginx-ns1-gslb
+else
+	CGO_ENABLED=0 GOOS=linux go build -installsuffix cgo -ldflags "-w" -o nginx-ns1-gslb github.com/nginxinc/nginx-ns1-gslb/cmd/agent
+endif
+
+test:
+ifeq ($(BUILD_IN_CONTAINER),1)
+	$(DOCKER_RUN) $(GOLANG_CONTAINER) go test ./...
+else
+	go test ./...
+endif
+
+lint:
+	golangci-lint run
+
+container: test nginx-ns1-gslb
+	cp $(DOCKERFILEPATH)/Dockerfile ./Dockerfile
+	docker build --build-arg CONFIG_FILE=$(CONFIG_FILE) -f Dockerfile -t $(PREFIX):$(TAG) .
+
+clean:
+	rm -f nginx-ns1-gslb
+	rm -f Dockerfile

README.md

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+# NGINX Plus - NS1 Global Server Load Balancing
+
+**nginx-ns1-gslb** allows [NGINX Plus](https://www.nginx.com/products/nginx) to connect with NS1 API to use [NS1 managed DNS](https://ns1.com/products/managed-dns) to create a Global Server Load Balancing solution that load balances connections or requests across two or more distinct data centers or points of presence (PoPs).
+
+## Prerequisites
+* At least 1 working instance of NGINX Plus reachable from the host where you are running this agent
+* NS1 API credentials
+
+## Configuration
+The configuration of the agent is managed by a YAML file. Check the [configuration](configs/README.md) readme for more information.
+
+The agent will try to open the file and configure itself, there might be 2 problems when doing this:
+
+* The file can't be opened (due to a bad path or file permissions)
+* The file is opened but the data can't be used (errors or missing required parameters)
+
+Both cases will make the agent fail to start with an error to describe the problem.
+
+## Running the agent
+
+### Locally (using Go >= 1.11)
+
+`go run cmd/agent/main.go --config-file <path/to/your_file.yaml>`
+
+This will run an Agent that fetches stats from one or more NGINX Plus instances, and updates the remote NS1 feeds. 
+
+### Docker
+
+1. Build the image specifying the config file:
+`make CONFIG_FILE=<path/to/your_file.yaml> container`
+
+1. Run the container:
+`docker run nginx/nginx-ns1-gslb:<version>`
+
+**Note:** consider the following while running the agent:
+
+* All NGINX Plus instances must be reachable and running when the agent is run for the first time.
+* While running, if at least 1 Instance of NGINX Plus is working, the agent will use the data from that one.
+* While running, if all NGINX Plus instances are off, the agent will send `{up: false}` to NS1 API for all the configured services.
+
+## Tests
+Run `make test` to run the tests. Set `BUILD_IN_CONTAINER` to 0 to run the tests locally instead of inside a container.

build/Dockerfile

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+FROM alpine:3.9
+ARG CONFIG_FILE
+
+RUN apk update && apk add ca-certificates && rm -rf /var/cache/apk/*
+
+COPY nginx-ns1-gslb /
+COPY ${CONFIG_FILE} /etc/nginx-ns1-gslb/config.yaml
+
+ENTRYPOINT ["/nginx-ns1-gslb", "-config-file", "/etc/nginx-ns1-gslb/config.yaml"]

cmd/agent/main.go

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+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/nginxinc/nginx-ns1-gslb/internal/agent"
+)
+
+var (
+	configFile = flag.String("config-file", "", "Path to the agent configuration file")
+)
+
+func main() {
+	flag.Parse()
+
+	if *configFile == "" {
+		log.Fatalf("config-file must be specified")
+	}
+
+	globalConfig, err := agent.ParseConfig(configFile)
+	if err != nil {
+		log.Fatalf("Error generating the config: %v", err)
+	}
+
+	a, err := agent.New(globalConfig)
+
+	if err != nil {
+		log.Fatalf("Error creating the agent: %v", err)
+	}
+
+	go handleTermination()
+	a.Run()
+}
+
+// handleTermination makes the agent exit on SIGTERM or SIGINT
+func handleTermination() {
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGTERM, syscall.SIGINT)
+	s := <-sigChan
+	log.Printf("%v signal received, shutting down the agent", s)
+	os.Exit(0)
+}