I am using a YML file to store trivial data.
I can create yml:
File.open("data.yml", "w") do |yaml|
yaml.write(#some_hash.to_yaml)
end
And open yml:
path = File.expand_path(File.dirname(__FILE__))
#trivial_data = YAML.load_file("#{path}/../../../config/data.yml")
But I don't know how to update a file. Say I want to add another row:
4:
agent_id: 332
last: Wade
first: Jason
suffix: Sr
rep_number: 2
How do I open, and update the yaml file? And is this a good idea on a production server?
Combine what you have and that's what you should do:
path = File.expand_path(File.dirname(__FILE__))
trivial_data = YAML.load_file("#{path}/../../../config/data.yml")
# ... manipulate data ...
File.open("data.yml", "w") do |yaml|
yaml.write(trivial_data.to_yaml)
end
You can't add something to a file without writing to it. YaML is a serialization language, and it doesn't make much sense to try and manipulate it directly. There is no simpler way (that I know of) that isn't horribly prone to errors.
Related
I'm doing one project for puppet, however currently stuck in one logic.
Thus, want to know can we fetch variable from .yaml, .json or plain text file in puppet manifest file.
For example,
My puppet manifest want to create user but the variable exist in the .yaml or any configuration file, hence need to fetch the varibale from the outside file. The puppet manifest also can do looping if it exist multiple users in .yaml file.
I read about hiera but let say we are not using hiera is there any possible way.
There are a number of ways you can do this using a combination of built-in and stdlib functions, at least for YAML and JSON.
Using the built-in file function and the parseyaml or parsejson stdlib functions:
Create a file at mymodule/files/myfile.yaml:
▶ cat files/myfile.yaml
---
foo: bar
Then in your manifests read it into a string and parse it:
$myhash = parseyaml(file('mymodule/myfile.yaml'))
notice($myhash)
That will output:
Notice: Scope(Class[mymodule]): {foo => bar}
Or, using the loadyaml or loadjson stdlib functions:
$myhash = loadyaml('/etc/puppet/data/myfile.yaml')
notice($myhash)
The problem with that approach is that you need to know the path to file on the Puppet master. Or, you could use a Puppet 6 deferred function and read the data from a file on the agent node.
(Whether or not you should do this is another matter entirely - hint: answer is you almost certainly should be using Hiera - but that isn't the question you asked.)
I want to edit file using chef cookbook recipe.
The file appears now as,
[attribute1]
foo=bar
[attribute2]
....
I want to change it like:
[attribute1]
foo=bar
newfoo=newbar
[attribute2]
....
So basically, I want to add a line if it does not exist in the file and I want to add it after a particular line in that file.
I found 2 options under Class: Chef::Util::FileEdit which could be useful here insert_line_after_match and insert_line_if_no_match. But I want an option which can perform both of the actions. If I use insert_line_after_match, it works for first run but for next run it just keep adding lines even if line is already in the file. And insert_line_if_no_match adds line at the end of file if line does not exist in file but I want to add line after particular line in that file.
I am bit new to chef recipes. Is there any solution to solve above problem?
I would suggest not editing files, but rather overwriting them. You should create a template or a file inside the cookbook and then using template or cookbook_file resource overwrite the file on the machine with the one from cookbook.
Your config file looks similar to toml, so you can also use toml-rb gem to generate this file from json (data bag) or attributes like that:
chef_gem 'toml-rb' do
compile_time false
end
file '/path/to/file.conf' do
content( lazy do
require 'toml'
"# This file is managed by Chef\n" +
TOML.dump( my_json )
end )
end
Pretty please don't use FileEdit. It is an internal API and not intended for public use. What you want is the line cookbook, specifically the replace_or_add custom resource. Make sure you craft your regexp very carefully.
In general we do not recommend this kind of management style as it is very brittle and easily broken by unrelated changed. A better option is to use a template resource or similar to manage the whole file in a convergent manner.
Is there a nice way to assert the contents of a CSV file in Ruby?
I understand how to use the CSV libraries and how to read in the CSV file, but that results in a long list of assertions such as:
`assert_equal("0", #csv_array[0].field('impressions'))
assert_equal("7", #csv_array[0].field('clicks'))
assert_equal("330", #csv_array[0].field('currency.GBP.commissions'))
assert_equal("6", #csv_array[0].field('currency.GBP.conversions'))
assert_equal("3300", #csv_array[0].field('currency.GBP.ordervalue'))`
Is there some sort of file comparator so I could write:
assert_equal(expected.csv ,actual.csv )
or something along those lines?
How about this:
expected_csv = "impressions,clicks,currency.GBP.comiisions,currency.GBP.conversions,currency.GBP.ordervalue
0,7,330,6,3300"
actual_csv = File.open('actual.csv').read
assert_equal(expected_csv, actual_csv)
That should work if the entire contents of the CSV file is only 2 lines. Otherwise you will have to manipulate actual_csv to get the parts you want to test. You could do that like so:
IO.readlines('actual.csv')[3]
That will get you the third line. You can then concatenate with a header line or compare to a string without the header.
If you have to test very output, you might find approval testing an interesting approach. Basically, the output is saved the first time your test runs. You can then check the output manually and approve it if correct. On subsequent runs, there will be an error when the output differs.
I created a quick and dirty method for doing this which I may clean up and turn into a gem at some point. https://gist.github.com/bpardee/513b4a15e5ebdc596e0b
For instance, the following code:
file = 'test.csv'
File.open(file, 'w') do |fout|
fout.puts "foo,bar,zulu\n1,2,3\n4,5,6"
end
assert_csv(file) do |csv|
csv << %w(foo bar warrior)
csv << [1,3,5]
csv << [4,5,6]
end
Would result in:
Missing columns: ["zulu"]
Unexpected columns: ["warrior"]
The following mismatches were found in line 2:
bar actual=3 expected=2
I don't recommend this for big csv files since everything is loaded into memory.
I want to replace properties in one file from those in another. (I am new to ruby, and read about Ruby and YAML. I have a Java background)
Eg.
File 1
server_ip_address=$[ip]
value_threshold=$[threshold]
system_name=$[sys_name]
File 2
ip=192.168.1.1
threshold=10
sys_name=foo
The ruby script should replace the $ values by their real values (I do not know if $[] is the format used in ruby. Also do Files 1 and 2 have to be YAML files, or erb files?) and produce File 1 as :
server_ip_address=192.168.1.1
value_threshold=10
system_name=foo
I searched the web for this, but could not express it in the right keywords to find a solution/pointer to a solution/reference material on google. How can this be done by a ruby script?
Thanks
If you can switch the formats, this should be as easy as:
require 'yaml'
variables = YAML.load(File.open('file2.yaml'))
template = File.read('file1.conf')
puts template.gsub(/\$\[(\w+)\]/) { variables[$1] }
Your template can stay as-is, but the substitution file would look like:
ip: 192.168.1.1
threshold: 10
sys_name: foo
This makes it easy to read in using the YAML library.
I'm trying to create a new file and things don't seem to be working as I expect them too. Here's what I've tried:
File.new "out.txt"
File.open "out.txt"
File.new "out.txt","w"
File.open "out.txt","w"
According to everything I've read online all of those should work but every single one of them gives me this:
ERRNO::ENOENT: No such file or directory - out.txt
This happens from IRB as well as a Ruby script. What am I missing?
Use:
File.open("out.txt", [your-option-string]) {|f| f.write("write your stuff here") }
where your options are:
r - Read only. The file must exist.
w - Create an empty file for writing.
a - Append to a file.The file is created if it does not exist.
r+ - Open a file for update both reading and writing. The file must exist.
w+ - Create an empty file for both reading and writing.
a+ - Open a file for reading and appending. The file is created if it does not exist.
In your case, 'w' is preferable.
OR you could have:
out_file = File.new("out.txt", "w")
#...
out_file.puts("write your stuff here")
#...
out_file.close
Try
File.open("out.txt", "w") do |f|
f.write(data_you_want_to_write)
end
without using the
File.new "out.txt"
Try using "w+" as the write mode instead of just "w":
File.open("out.txt", "w+") { |file| file.write("boo!") }
OK, now I feel stupid. The first two definitely do not work but the second two do. Not sure how I convinced my self that I had tried them. Sorry for wasting everyone's time.
In case this helps anyone else, this can occur when you are trying to make a new file in a directory that does not exist.
If the objective is just to create a file, the most direct way I see is:
FileUtils.touch "foobar.txt"
The directory doesn't exist. Make sure it exists as open won't create those dirs for you.
I ran into this myself a while back.
File.new and File.open default to read mode ('r') as a safety mechanism, to avoid possibly overwriting a file. We have to explicitly tell Ruby to use write mode ('w' is the most common way) if we're going to output to the file.
If the text to be output is a string, rather than write:
File.open('foo.txt', 'w') { |fo| fo.puts "bar" }
or worse:
fo = File.open('foo.txt', 'w')
fo.puts "bar"
fo.close
Use the more succinct write:
File.write('foo.txt', 'bar')
write has modes allowed so we can use 'w', 'a', 'r+' if necessary.
open with a block is useful if you have to compute the output in an iterative loop and want to leave the file open as you do so. write is useful if you are going to output the content in one blast then close the file.
See the documentation for more information.
data = 'data you want inside the file'.
You can use File.write('name of file here', data)
You can also use constants instead of strings to specify the mode you want. The benefit is if you make a typo in a constant name, your program will raise an runtime exception.
The constants are File::RDONLY or File::WRONLY or File::CREAT. You can also combine them if you like.
Full description of file open modes on ruby-doc.org