Shulou(Shulou.com)06/01 Report--

This article mainly introduces "how to configure Nodejs on the CentOS6.x server". In the daily operation, I believe that many people have doubts about how to configure Nodejs on the CentOS6.x server. The editor consulted all kinds of materials and sorted out a simple and easy-to-use method of operation. I hope it will be helpful to answer the doubt of "how to configure Nodejs on the CentOS6.x server". Next, please follow the editor to study!

First create a playbook file, and we'll try to keep it simple.

-hosts: all tasks:

Define some hosts running this playbook, and then list a series of tasks below.

1.1 add additional sources

When preparing to apply a server, administrators often add additional sources first to ensure that specified software packages are available or in the * * version.

In the following script, we want to add EPEL and Remi sources so that we can get a package similar to node.js. If you use the shell script to handle it, it looks like this.

# Import Remi GPG key-see: http://rpms.famillecollet.com/RPM-GPG-KEY-remi wget http://rpms.famillecollet.com/RPM-GPG-KEY-remi\-O / etc/pki/rpm-gpg/RPM-GPG-KEY-remi rpm--import / etc/pki/rpm-gpg/RPM-GPG-KEY-remi # install Remi repo Remi repo contains many PHP extensions rpm-Uvh-- quiet\ http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

# install EPEL source

Yum install epel-release

# install Node.js (npm + and its dependencies)

Yum-enablerepo=epel install npm

This shell script is used to import the GPG keys of EPEL and Remi, then add the source, and * install Nodejs. This is fine for simple deployment, but it's a stupid way to run so many commands, and if you accidentally disconnect, your script will stop. And what if your script is just about to be finished at this time?

Tip: if you want to skip the specified step, you can skip the step of adding GPG keys, just add-nogpgcheck when running the command. Or in Ansible, the disable_gpg_check parameter is set to yes in the yum module, but GPG keys is still added. With GPG, you can know who the author of the package is, whether the package has been modified or not, and do not disable GPG checking unless you know what you are doing.

Ansible makes things more robust, and the following example of using Ansible is more detailed, which has the same functionality as the shell script above, but is easier to understand and more structured. Ansible variables and other useful features are used below. Then the playbook above, let's move on.

Tasks:-name: Import Remi GPG key rpm_key: "key= {{item}} state=present" with_items:-"http://rpms.famillecollet.com/RPM-GPG-KEY-remi"-name: Install Remi repo. Command: "rpm-Uvh-- force {{item.href}} creates= {{item.creates}}" with_items:-href: "http://rpms.famillecollet.com/enterprise/remi-release-6.rpm" creates:" / etc/yum.repos.d/remi.repo "- name: Install epel repo yum: name=epel-release state=present-name: Stop the firewall service: name=iptables state=stopped-name: Install NodeJS and npm yum: name=npm state=present enablerepo=epel

Let's take a look at the specific steps.

Rpm_key is an Ansible module used to add or remove GPG key from your RPM database. We are importing a key from the source of Remi.

Because Ansible does not have the rpm command, we use the command module to use the rpm command, so we can do two other things. A) use the creatse parameter to tell Ansible when not to run the command, and in this example, we tell Ansible that those files will be created after the command is executed successfully. When this file exists, the command will not run. B) use with_items to define a URL and a file for creates checking.

Yum is responsible for installing the EPEL source.

Because we will use this server for testing, we use the service module to disable the system firewall and prevent it from interfering with our testing.

Yum installs Node.js (also installs npm,Node's package manager), we use enablerepo to specify that it is searched in the EPEL source, and of course we can use disablerepo to specify which source (repository) is not used.

Because NPM is now installed, we use Ansible's npm module installation Node.JS tool forever,forever to run our app, set global to yes, tell NPM that the installation module is in the / usr/lib/node_modules location, and then all users can use it.

We already have a Node.js app server, so let's deploy a simple Node.js app that responds to HTTP requests on port 80

1.2 deploy a Node.js app

This step is to deploy a simple Node.js app on our server. First, by creating a new folder, we create a simple Node.js app that is in the same path as the ymal file above you. Then create a new file, app.js, and in this folder, edit the following file

/ / app.js / / load the express module. Var express = require ('express'), app = express.createServer (); / / response "/" request is' Hello World'. App.get ('/', function (req, res) {res.send ('Hello World! Yunzhonge');}); / / listen like a real server on port 80 app.listen (80); console.log (' Express server started successfully.')

Don't worry about the grammar of node.js and our case. We need a quick deployment case that can be written in Python,Perl,Java,PHP or other programming languages, but because Node is a very simple language that runs in a simple lightweight environment, it is a very good language to test your server.

Because this little app depends on Express (a simple Node HTTP framework), we also need to tell NPM about its dependency through a package.json file, which is under the same path as app.js.

{"name": "examplenodeapp", "description": "Example Express Node.js app.", "author": "yunzhonghe", "dependencies": {"express": "3.x.x"}, "engine": "node > = 0.10.6"}

Then add the following to your playbook, copy the entire app to the server, and then let npm download the dependencies (here is express.)

-name: Ensure Node.js app folder exists. File: "path= {{node_apps_location}} state=directory"-name: Copy example Node.js app to server. Copy: "src=app dest= {{node_apps_location}}"-name: Install app dependencies defined in package.json. Npm: "path= {{node_apps_location}} / app"

First we use the file module to make sure that the app directory we installed exists. The {{node_apps_location}} variable can be defined in the vars section, and the vars part is located at the top of the playbook. Of course, it can also be defined in inevntory or when running ansible-playbook.

We use Ansible's copy module to copy the entire app folder to the test server, and the copy module can intelligently distinguish between a single file and a directory that contains files, and then recursively in the directory, like rsync or scp. Ansible's copy module works well with a single file or a small number of files, but if you copy a large number of files and nest several layers of directories, the copy module is not competent. In this case, if you want to copy the entire directory, you * consider using the synchronize module, if you want to copy an archive, then expand it, * use the unarchive module.

In the third step, we use the npm module, this time with no additional parameters other than the path of the app. This tells NPM to parse the package.json file and then make sure that all dependencies exist.

It's all done. * one step is to start the app.

1.3 run a Node.js app

We now use forever to start the app.

-name: Check list of running Node.js apps. Command: forever list register: forever_list changed_when: false-name: Start example Node.js app. Command: "forever start {{node_apps_location}} / app/app.js" when: "forever_list.stdout.find ('{node_apps_location}} / app/app.js') =-1"

In this play, we do two new things.

Register creates a new variable, forever_list, so that the next task can be used to determine whether the next command is allowed to run. Register is used to save the output of the command, including standard output and error output, and then assigned to the variable name.

Changed_when tells Ansible when the play will cause a change. Here, the forever list command will never cause the server to change, because we specified false.

The second play actually starts the app using forever. We can start this app by calling node {{node_apps_location}} / app/app.js, but this is more difficult to control.

Forever tracks the Node app it manages, and then we use the list option of Forever to print a series of running app. When we run the playbook for * times, the list is obviously empty, but it will run after it is judged to be empty. If the app is running, we will not start another instance. To avoid this situation, we use the declare statement to specify that when the path of the app is not in the output information of the forever list, we start the app.

1.4 Node.js app server summary.

At this point, you have finished playbook, and then install a simple Node.js app to respond to HTTP requests on port 80.

To run the playbook on a server, use the following command to pass the node_apps_location variable through the command

Ansible-playbook-extra-vars= "node_apps_location=/usr/local/opt/node"

When the server finishes configuring and deploying the server, specify the hostname of the test server in the browser to view the effect

Simple, but effective, we have configured a Nodejs application server in a YMAL file with less than 50 lines

This is the end. Thank you very much for your attention.

1.5 question

Question1: when I was deploying nodejs app for 100 servers, when 20 were interrupted, I would re-execute it. What is the process of the previously installed software package, will the configuration be re-executed or skipped? Trouble Daniel answer

Answer: Ansible has its own idempotent feature so that it can effectively ensure the safety and reliability of all operations. In case of execution failure, it will automatically generate a list of corresponding error servers in the home directory through-- limit to complete the rest of the work.

Question2: is the hero's nodejs deployed through tools? Npm is so complicated.

Ha, the configuration of npm is one-off. Confirming the initial configuration is time-consuming and troublesome. Yum or npm has its own advantages and disadvantages, depending on the business.

Question 3:-- extra-vars=, are there many applications in enterprises?

A: more, at least it has been used in our work all the time. As you can see from the sharing in previous issues, this parameter has been used a lot. But what is introduced on the official website has been replaced by one. It is still suggested that we should use more.

Question 4: when I perform a task through ansible, there will be the reason why the task has been stuck for a long time. Where do I need to check again?

A: many friends have been asking about this problem all the time. According to their personal experience, I suggest the following aspects for investigation:

It is true that the current command execution time is not long.

Pong detects server survival

Some commands need to connect to the external network to download updates that take a long time to check the broadband of the network.

-vvv is a very good way to troubleshoot

If there is no solution, shorten the execution time of the operation in / etc/ansible/ansible.cfg and wait for the final end of the attempt.

At this point, the study on "how to configure Nodejs on the CentOS6.x server" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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